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FAQs on  Corydoras Cat Environmental Disease

FAQs on: Corydoras Catfish Health 1, Cory Disease 2, Cory Disease 3, Cory Disease 4
FAQs on Corydoras Catfish Disease by Category
: Nutritional (e.g. HLLE), Social, Infectious (Virus, Bacterial, Fungal), Parasitic (Ich, Velvet...), Genetic, Treatments,
Related Articles: Callichthyid CatfishesSummer loving: cats in the garden, kittens in the kitchen by Neale Monks,

FAQs on: Corydoras Catfish 1,
Corydoras Catfish Identification, Corydoras Catfish Behavior, Corydoras Catfish Compatibility, Corydoras Catfish Stocking/Selection, Corydoras Catfish Systems, Corydoras Catfish Feeding, Corydoras Catfish Reproduction,
FAQs on: Panda Corydoras, Pygmy Corydoras spp.,

FAQs on:
Callichthyids 1, Callichthyids 2,
FAQs on: Callichthyid Identification, Callichthyid Behavior, Callichthyid Compatibility, Callichthyid Selection, Callichthyid Systems, Callichthyid Feeding, Callichthyid Disease, Callichthyid Reproduction, Catfish: Identification, Behavior, Compatibility, Selection, Systems, Feeding, Disease, Reproduction

Soft/er, acidic water, sans much in the way of dissolved wastes.

Some species more tropical than others; most are cooler (low to mid seventies F) water

Soft, smooth sand... not round pebbles or sharp like silica.

Cory health in 15-gal column tank      5/3/17
Hello Team, I searched the archives and I can't find this one.
I was hoping for some help with Corys in my tank. I have had a 15-gallon column tank for two years, with a single Opaline Gourami, five cherry barbs for a year (three m, 2 fem), and two (avg.) non-dwarf Corys. I feed flakes and float pellets once daily, a sinking shrimp pellet every few days, and freeze-dried bloodworms once a week. My ammonia and nitrite levels are zero and my temp hovers around 77 degrees. I filter with an AquaClear 20.
<Mostly sounds fine...>
I seem to only manage to get a 6-month lifespan from my corys, regardless of the breed. This seems short; when one passes, I buy a new pair to avoid loneliness, and the cycle continues. Just today, I have a single one again. (1) should I purchase a single or a pair more corys if any, and (2) am I doing something wrong or are corys simply a bad idea in this configuration?
<Corydoras are basically sound fish, but they do have a couple weaknesses.
Firstly, they're low-end tropicals. A good temperature range for most species is 22-25 C/72-77F. Corydoras sterbai is the one widely trained warmer water species. Anyway, the warmer the water, the more oxygen they
need. This brings us to the second point, their need for air. If the tank is too deep, they can't easily swim to the top to gulp air, and this in turn leads to stress. I don't think a 15 gallon tank is likely to be too deep, but if there's something stopping them swimming, like a strong current or aggressive/nippy midwater fish, it might have an effect on them.
Finally, there's the oxygenation of the substrate. If the bottom of the tank has poor water movement, the substrate can become anaerobic, and together with microscopic scratches to their whiskers and fins, Corydoras become sickly, listless, and may well die. So short term: I'd clean the substrate, I'd check the water flow, I'd lower the water temperature, and I'd check none of the other fish are harassing them.>
I know they should be kept in larger groups but I don't want to crowd them on the small floor. Should I choose another scavenger instead?
Bristlenose catfish seem too "dirty".
<They are not messy at all, given their size; but they're also pretty rubbish scavengers, being more or less algae-consumers. I find Whiptails a much better substitution for Corydoras. Standard issue Rineloricaria species are sociable, hardy, and long-lived.>
Any insight would be greatly appreciated. Thank you for all you do!
<Hope this helps, Neale.>
Re: Cory health in 15-gal column tank      5/4/17

Great advice, thanks Neale. I think I might give the whiptail a shot, as you suggested. For this columnar tank setup, so you think I should go for one or two?
<Definitely more fun kept in groups. Males hold little territories (like a crevice in a bit of bogwood) when breeding but otherwise Rineloricaria species do seem to be sociable much of the time. Singletons can do fine though, they just aren't as much fun. Do note that Whiptails are day-active, and prefer sandy substrates where they can bury themselves in at times. They will also change colour on sandy substrates, which is very cool to see! Underrated fish, I think because they *look* delicate -- even though they're actually quite hardy animals.>
<Cheers, Neale.>

Peppered Cory Illness      7/1/16
<Am responding here for timeliness-sake, but asking Neale Monks to respond as well>
Hello, I have been assisted by your staff in the past for some issues with angelfish, so I thought I might get some help with my Corys. I have the following setup:
55 Gallon
Artificial Plants
Sand substrate
Fluval 305 Canister Filter
5 Corys (3 Peppered and 2 Green)
5 Neon Tetras
5 BN Plecos
4 Silver Dollars
1 Male Betta
Food: Crisps, algae wafers (veggie and protein) daily. Betta gets a small amount of "Betta Food Pellets". Weekly offerings are bloodworms and/or Tubifex worms. Plecos LOVE cucumbers and the silver dollars enjoy romaine lettuce leaves.
I do 50% water changes every week and clean my canister filter every 2 weeks (suggested is once a month but I do tend to overfeed with the silver dollars). Two of my peppered Corys are ill. Both have turned a dark, almost, black. Listless, no eating.
<Mmm; something environmental at play here... introduction of a pollutant?

With the lettuce perhaps... I take it the insect larva and worms you're feeding are processed... Not live>
The larger of the two (female) is at least 3" long and she's just over 6 years old. The smaller (male) is about a year old and he is the same. The female has ragged fins and the male has a "scrape" on one side of the his tail where the paler "flesh" is showing and for a day or two had a red ring around the lower half of his eye orbit.
<Physical trauma? From... the Dollars? The Plecos?>
That has disappeared. The only outward sign of illness I have noticed is the female had an episode of her chronic swim bladder disease. From time to time (every 6-8 months), she will float to the water's surface and end up laying on her side for part of the day. I always withhold food and within 8 hours, she's great again. This happened last week. I was unable
to do my regular weekly water change last Saturday, because I had the flu.
So, my parameters are as follows:
pH 7.5
Nitrate: 5
Nitrite: 0
Ammonia: 0
<Water temp.?>

The female is my favorite fish. She's typically happy and LOVES water changes. She is just listless and I think she may have a little spot on her forehead, but I really can't tell with the dark color. I would sincerely appreciate any advice you can offer. All the other fish in the tank are happy and acting normally. I do notice some dark-looking (dark brown) algae or slime just beginning to form on my plastic plants, but this is something that I get regularly and clean each week.....
PS - Going to attempt to get a couple of pics to send as well
Kristi A. Jones
<Bob Fenner>
Peppered Cory Illness /Neale      7/1/16

Hello, I have been assisted by your staff in the past for some issues with angelfish, so I thought I might get some help with my Corys. I have the following setup:
55 Gallon
Artificial Plants
Sand substrate
Fluval 305 Canister Filter
5 Corys (3 Peppered and 2 Green)
5 Neon Tetras
5 BN Plecos
4 Silver Dollars
1 Male Betta
Food: Crisps, algae wafers (veggie and protein) daily. Betta gets a small amount of "Betta Food Pellets". Weekly offerings are bloodworms and/or Tubifex worms. Plecos LOVE cucumbers and the silver dollars enjoy romaine lettuce leaves.
I do 50% water changes every week and clean my canister filter every 2 weeks (suggested is once a month but I do tend to overfeed with the silver dollars). Two of my peppered Corys are ill. Both have turned a dark, almost, black. Listless, no eating. The larger of the two (female) is at least 3" long and she's just over 6 years old. The smaller (male) is about a year old and he is the same. The female has ragged fins and the male has a "scrape" on one side of the his tail where the paler "flesh" is showing and for a day or two had a red ring around the lower half of his eye orbit.
That has disappeared. The only outward sign of illness I have noticed is the female had an episode of her chronic swim bladder disease. From time to time (every 6-8 months), she will float to the water's surface and end up laying on her side for part of the day. I always withhold food and within 8 hours, she's great again. This happened last week. I was unable
to do my regular weekly water change last Saturday, because I had the flu.
So, my parameters are as follows:
pH 7.5
Nitrate: 5
Nitrite: 0
Ammonia: 0
The female is my favorite fish. She's typically happy and LOVES water changes. She is just listless and I think she may have a little spot on her forehead, but I really can't tell with the dark color. I would sincerely appreciate any advice you can offer. All the other fish in the tank are happy and acting normally. I do notice some dark-looking (dark brown) algae or slime just beginning to form on my plastic plants, but this is something that I get regularly and clean each week.....
PS - Going to attempt to get a couple of pics to send as well
<<Would start by reviewing the environment, as Bob suggests. Corydoras paleatus is a low-end tropical species that can be stressed by overly warm conditions; 22 C/72 F is ideal, and if you're keeping other tropicals that like cooler water (such as Danios, Neons, Swordtails and Platies) then doing a good-sized water change with cooler water can pep the fish up. If cooling the tank isn't an option, add an airstone and/or another filter, because lack of oxygen rather than raw temperature is the thing that stresses them. Ditto more frequent water changes just to improve conditions generally. Now, reddish or whitish flecks on the fins and between the armour plates (scutes) is usually a sign of bacterial infection. Early on, the sorts of antibiotics used for Finrot can work nicely. There's something called Corydoras "Red Blotch" Disease that does plague these fish from time to time. It's probably triggered by an environmental shortcoming of some sort. I've written about the disease over at Fish Channel, here:
Take a read. Hope this helps, Neale.>>
Re: Peppered Cory Illness      7/1/16

THANK YOU BOTH! I took some pics at lunch. They are attached. Perhaps temperature is an issue. I had been keeping the tank at 78-80 for angels that I previously kept (gave that up - no luck with that breed of fish), and I do recall my peppers doing much better with cool water at 72-74.

Oh, if it could be that simple.....please let me know what you think. I know my tetras and Plecos do great at lower temps....I believe the silver dollars will as well.
<They should; yes>
The pic of my female Cory on the red gravel substrate was within the first couple of months after I adopted her from my brother. I thought this would be helpful for comparison. THIS is what I'm used to seeing with her....and the changes may be subtle, but she's very special to me. The remainder of the pictures were taken today. The fish with the skinned up tail section (last two attachments) is the little male. The rest are of my female. The torn fins could be the result of the horrible advice I received 2 months ago from my LFS when they suggested tiger barbs would be good in this tank..... wow, were they wrong.
<Oh yes; too nippy>
I had those guys less than 5 days and they were ravenous, BUT I don't recall seeing any of this fin damage. When I compare the two pics of my female, her eyes may look a bit enlarged? She's always had such large ones....
<Both the before and current pix eyes are indeed too large>
I will definitely do a 50% water change tonight and slowly lower the temperature.
I'm pretty careful with the lettuce and Cukes, but please let me know if there is a specific manner of cleaning these foods before adding to the tank.
<Soak them in tap water over night before offering. DO test the soak water for nitrates... telling>
I typically serve raw after about a 2 minute thorough rinse under lukewarm water.
<Again; the soak>
THANKS again, you folks are SO knowledgeable and it is extremely reassuring to have a source of experience to go to in these times of illness with our little finned friends.
<A pleasure to share; offer aid to other aquarists, humans who would better their understanding>
Kristi A. Jones

Re: Peppered Cory Illness /Neale       7/2/16
Thank you! Will follow all suggestions and let you know how they do....just two more questions:
1. Do you see evidence of an infection in the body condition of either fish?
<You can't really tell this by looking at a photo. I'd assume so, and medicate as per bacterial infection. It won't do any harm, and will help if bacteria are at play here.>
2. Do you feel the large eye issue is PopEye or is there something I need to do to that end?
<Pop-eye tends to fix itself when environmental issues improve, and assuming a secondary bacterial infection doesn't set in (again, another good reason to use anti-bacterial medications). Corydoras do get a bit "bug-eyed" when stressed, but usually recover from illness well, if the problem is caught early. Epsom Salt helps Pop-eye, so again, I'd do this alongside the antibiotics, as previously discussed.>
Much appreciated!
<Welcome. Neale.>

Please help my panda Cory!      11/14/15
Mature tank, 30 gallons, 5 panda Corys, 3 zebra Otos, an African dwarf frog, 7 mosquito Rasboras, some amano shrimp, Eco Complete gravel substrate,
<Ah, this might be the problem!>
planted tank, Aqueon 30 filter, TopFin 10 filter, 20% water changes weekly, 7.0 pH, Ammonia 0 ppm, Nitrite 0 ppm, Nitrate 2.0 ppm
In the past 2 days, one of my panda Corys' barbels have almost completely eroded and today he has developed a white fuzzy cotton-looking patch on his head. He is lethargic, not eating, and stays away from the other Corys.
I'm worried that this could be columnaris because I have noticed tiny white things on the glass that sway with the current. Or do you think it might be a bacterial infection that has also developed a fungal infection? The other 4 panda Corys are acting completely normally and look healthy. What should I do?! I would hate to lose this little guy!
<How abrasive does the gravel feel to you? Here's the thing. Barbels erode because of a combination of physical damage (caused by sharp substrates) and subsequent bacterial infection (very similar to Finrot). Unfortunately for the Amano 'Nature Aquarium' brigade, substrates that plants like are replicated using quite abrasive materials, often byproducts from the
glassmaking industry. While not a problem for tetras, Otocinclus and shrimps, anything that roots about in the substrate, like Corydoras, is going to be less happy. Corydoras not only sift the substrate with their barbels, they like to stick their heads right in and swallow the substrate, spewing it out of their gills. It's adorable when they do it on a sandy substrate, but isn't going to work on traditional gravel or sharp sand. So, in situations where Corydoras are being kept, you're almost always better off keeping them on smooth lime-free sand (smooth silica sand or pool filter sand work well, and cheaply) or else the finest, smoothest pea gravel you can find. There's nothing to stop you using a plant friendly substrate underneath a gravel tidy (basically a plastic mesh) and then add 1 cm or so of the catfish-friendly substrate on top. Plants couldn't care less. Might need to make a few holes in the gravel tidy for plants with deep roots, but most plants will happily send their roots through the mesh in time. Anyway, this would be my first line of thought: is the substrate at fault. Try quarantining the suspect catfish in a tank with no substrate (8-10 gallons is ample for one or a few Corydoras, temporarily at least)
and see if they recover (medicating as per Finrot). Make sense? Neale.>
Re: Please help my panda Cory!

Absolutely. I'll try that first.
<Cool. Neale.>

Sick Albino Corydoras
Hello and thank you for taking the time out to read this. I am writing regarding an albino Corydoras catfish whom I recently rescued from poor living conditions at a local pet store.
<A kindness, but sometimes misguided: if a fish dies in an aquarium shop, that's a loss, and the owner will be less likely to buy that species; if the fish is sold, even if it's unhappy, the owner sees a profit, and re-ordering that species is likely. If you see a pet shop not caring for its livestock, then contacting the body that issues animal sales licenses is the best step forward, often a city or state government agency.>
To be honest, I am not a preferable candidate to take on such a task. I only recently (2 weeks ago) started my first tank (10 gallon).
<A bit small, but certainly viable for a small group of Corydoras, perhaps 3-4 specimens rather than a full school of 6+.>
Solely following the advice of a pet store employee, I soon learned that I had made mostly poor choices. I am diligently trying to learn as much as I can, while attempting to cycle my tank using SeaChem stability and prime.
My tank inhabits 3 albino Corydoras, 2 Danios, 2 mystery snails and 2 cherry shrimp.
<The snails and shrimps were bad choices. But the Corydoras and Danio combination is a good one -- though again, 10 gallons is a bit small for such active and quite big (5 cm/2 inch) fish.>
I have various aquatic plants and recently upgraded to an internal power filter for tanks up to 30 gallons (after adding the sick Corydoras to my tank, I thought it would be safest to increase filtration since my tank is not yet cycled).
<Some merit in that. Adding some Floating Indian Fern would be a very good idea. These jump start the filtering process and also remove some pollution directly, so are always worthwhile. They also inhibit algae.>
Originally I quarantined the sick Cory since I honestly had no idea what could be wrong with him. He was pale, listless and would enter what appeared to be periods of paralysis, which lasted for up to 4 hours. I thought he had died multiple times during his 3 days in confinement. Then suddenly he would dart around his tank and remain active for a short time.
He had red streaks/blotches on his body, darted to the surface for air often and would lie on his side motionless.
<These red blisters are suggestive of "Corydoras Plague" or "Red Blotch Disease", which is (probably) a bacterial infection seen in stressed and damaged bottom dwelling fish. A combination of improving the substrate (removing sharp sand/gravel), improving water quality, and treating as per Finrot usually helps.>
His gills would either appear to be deeply pulsating or not moving at all.
During his time alone in his small tank, I was treating the water with prime and stability. I was also changing 50% of the water daily and keeping everything as clean as possible. He did not eat (I tried almost every option possible) and he did not even acknowledge food when it was right in front of him. I forgot to mention that his barbels are very short, barely visible even.
<Again, a very good indicator of bacterial infection caused by the wrong environment. In brief: sharp sand or gravel damages the whiskers; poor water quality inhibits the immune response; bacteria infects the wounds;
the whiskers erode away.>
I only found your site today and this was after I made the bold (and possibly foolish) move of transferring my sick Cory to my 10 gallon tank. I posted endless requests for help on so many forums, but received very vague responses. Through research, my best guess is that the Cory had ammonia poisoning. After day 2 of confinement, his red blotches were gone and he no
longer displayed long periods of paralysis.
Although not nearly as active as my 2 healthy Corydoras, there was a significant improvement. Without any guidance and a true lack of knowledge, I convinced myself that he was depressed, lonely and recovering from ammonia poisoning. I have read that Corydoras should be in groups, so I moved him to the larger tank in hopes that the company would influence him
to thrive.
<Certainly wise. Red Blotch Disease isn't contagious as such, and is more to do with the catfish being stressed/damaged than "catching" something.>
My sick Corydoras has only been in the larger tank for about 15 hours, but he seems to be doing well. He has definitely taken to the other Corys and spends time grazing, swimming and even EATING with them(first time eating since I brought him home). However, he still appears pale and appears lethargic at times. I am very nervous that my irresponsible and uneducated choices will take a turn for the worst. I worry that I made the wrong choice for both the sick Corydoras and the rest of my fish. I am hoping you wouldn't mind offering some insight and advice. My only plan of action is to continue with daily water changes along with treatments of stability and prime. I have been testing parameters using test strips so far, but today I purchased the API testing kit. Once I learn how to use it I can offer better details on water conditions. My test strips have been showing values of 0 for both nitrates and nitrites(I started stability about 4 days ago).
Ammonia levels have remained at zero. I don't have the specific value on hand for hardness, but the key showed it to be in the "hard" range. My pH has been at 7.2 I believe. The alkalinity was very low.
<Corydoras are very adaptable: provided water chemistry is stable, it doesn't matter much what the precise values are within, say, pH 6-8, 1-20 degrees dKH. Don't overheat Corydoras though: 25 C/77 F is optimal for sick specimens, a degree or two cooler for maintenance. Incidentally, 24 C/75 F would be ideal for Danios, Cherry Shrimps and Apple Snails!>
The strips don't offer exact numbers unfortunately, so I apologize. I will get working on the API kit so that I can offer more details if/when needed.
Thanks again for taking the time to read this. I apologize if I left anything out. Sincerely, Danielle
<See above. Reviewing the environment and using an antibiotic should help.
Cheers, Neale.>

Re: Sick Albino Corydoras     7/20/15
Hello again, Thank you so much for the prompt reply. I was honestly expecting a bit of criticism in your response, but was very relieved that my choices were not (completely)ignorant to say the least.
Since my last email, my recovering Cory is doing fantastic (whom, by the way has taken on the name "Casper" not only for his albinism (obvious), but also for the multiple instances that he appeared to have come back from the dead =) ).
<So not named after Caspar Weinberger then?>
His improvement has been so ideal that I have yet to pursue treatment with an antibiotic. This decision was just that of a mothers intuition I suppose, since I avoid unnecessary drugs/chemicals within my own family. If you feel that proper treatment is still necessary despite his progress, please let know.
<If a fish is healing under its own steam, then no, there's no need to use medication. But do be on the look out for relapses and act accordingly.>
In the last few weeks I have fallen in love with this enjoyable responsibility/hobby, especially with my 3 sweet little Corydoras. How anyone can resist their innocent nature or the way they blink at you through the glass is beyond my comprehension (*Love*)!
<Certainly entertaining fish. The blinking is, of course, an adaptation to living in a muddy environment, where regular blinking helps to wipe away silt from the surface of the eyeball. Fish don't (with a few exceptions) have anything comparable to our eyelids, so they aren't self-cleaning in the same way (indeed, in an aquatic environment it's not normally necessary; eyelids are an evolutionary response to using fish-type eyes in a dry air environment).>
I have spent an unreasonable amount of time (while juggling a toddler) reading through the contents of your site. That being said, I purchased a 29 gallon tank today and what I understand to be equivalent necessities for the cycling process.
<An excellent size aquarium. Can't go wrong with 20-30 gallon tanks. A nice balance between size, cost and stability.>
I would love to do it the right way this time and provide a desirable home for my current fish while adding to my small group of Corydoras.
<Provided the filter is an internal or external filter, you simply swap from one tank to the other (switched off while it's out of the water though!). Transferring some/all of the aquarium water is a plus too, as well as substrate, plants, etc. All this will jump start the new tank instantly. Easy!>
In response to your comments I am also considering transferring the cherry shrimp to a small species tank, so thank you for that insight.
<Agreed: mixing Cherry Shrimps with some other 'nano' species in the 10 gallon would be great. An unheated tank stocked with Cherry Shrimps and subtropical species such as Least Killifish would be highly entertaining. I have just such a tank in the kitchen. Trivial to maintain, cheap to run, and some babies of both species too!>
So this is where my questions and/or current understanding comes in to play(please correct anything I may have misinterpreted)! The internal power filter that I am currently using has both sponge and carbon components (I also added ceramic rings). After reading your articles on freshwater filtration and media, I understand it would be best to replace the carbon cartridges with filter wool.
<Yes; carbon has only one function, removing unwanted chemicals, and for most aquarist, this is pointless. It'll remove medicines just as well, making it a positive hazard if you have sick fish.>
I mentioned in my last email that I am cycling with fish using stability and prime. My values are improving and I seem to be on the right track with my 10 gallon tank. Would you recommend that I use the stability in the fishless cycling of my 29 gallon tank?
<See above. Just swap the filter (and the fish) to the 29 gallon tank. If you can, put an equivalent filter in the 10 gallon, and cycle that one using Cherry Shrimps, which generally sail through the process if you don't add any food beyond allowing them to graze algae.>
Another concern of mine seems to be an overly covered topic on your site (and I genuinely apologize for adding to it). Since the Corydoras are at the top of my new infatuation, I am going with a sand substrate in the upgraded tank. I was unable to find silica sand sold locally.
<In the US, often sold as pool filter sand.>
Anxious to start the cycling process (and help Casper regenerate his lost whiskers asap), I purchased an adequate supply of sand by CaribSea called super naturals. I believe it to be appropriate for the cories based on what I've researched, but would appreciate any opinion you may have to offer on this product.
<Provided the packaging says "suitable for soft belly fish" or "suitable for sand sifting fish" or something along those lines, you're fine. Carib Sea used to expressly state this on their website, yes or no for each of its brands/products, but it's been updated and this information dropped. In any case, you're after a fine, smooth substrate different from sharp sand.>
I am worried that the maintenance of such a fine sand may be a bit beyond my experience level (when adding in the full time care of a feisty toddler and the final semester of a nursing program).
<It's easy to maintain. Silt sits on top of sand. It sinks into gravel. So in a gravel tank, the dirt is "out of sight, out of mind" but it doesn't vanish. Cheap tip: buy a turkey baster and use this to spot clean the tank whenever you see piles of gunk you can't ignore. For what it's worth, Corydoras don't mind a bit if mulm -- it's what they mostly consume in the wild.>
If you have no personal opinion on this specific product, please feel free to disregard (with much understanding). Finally, I have made a hypothetical observation with my albino Corydoras regarding possible sensitivity to light. It is somewhat hard to describe their behavior when the (led) lights have been shining down on them for a while. If I had to compare the symptoms to those of a human, I would say it appears as if they are experiencing absence seizures (2 of the 3, including Casper).
<Seems plausible. Review human albino eyesight, and for fish, it's probably similar, except of course water cuts out UV light almost completely. Corydoras are naturally shade-dwelling fish, and the addition of floating Indian Fern makes them a lot happier that bright overhead light.>
They have been unresponsive to firm taps on the glass while lying right beside it. Then a fraction of a minute later, upon tapping they suddenly jolt to the other side of the tank and all over for a few moments. They don't behave this way when the led lighting is off. Is this an issue that you've ever been made aware of regarding albino species and bright lighting?
<Yes; it is widely observed by objective fishkeepers that albino fish are less robust than their normal relatives. We've bred them because they look nice (to some people, anyway) but such fish wouldn't last long in the wild.>
In addition, my tank is planted with plenty of hiding spots. Even so, when the lights are on the 2 cories choose to remain unsheltered, eventually entering this odd "hypnotic" state. I find it odd that they don't try to hide if it's bothering them.
<Corydoras are not very smart. Causes problems if kept with territorial fish -- they simply fail to learn to avoid territories.>
In a way, to me this makes their behavior seem even more similar to that of am unsuspecting epileptic.
<Not beyond the realms of possibility. Fish behaviour is both more complex than we assumed even 20 years ago but also far less well studied than that of mammals or birds. We're observing all sorts of things we never expected with fish, such as play behaviour (hitherto associated with "higher" vertebrates) as well as what appears to be the ability to feel pain (this latter still contentious, but if it's true, profound in terms of how we catch fish to eat and keep fish as pets).>
I have added 3 pictures of Casper - the first 2 while quarantined and at his worst. The 3rd at his best state so far, taking a rest after playing with the other (not the best quality, but notable to his improved color and "plumpness"). Just proud of him and thought I'd share :) !
<Looking better than last time!>
Thanks so much again for your time and all the very valuable information on your amazing site. It has been quite the life saver for my fish (as well as my own sanity!).Danielle
<Most welcome. Neale.>

Cory playing dead 11/5/10
Hi Crew,
Thanks for all the great work you do. I'm hoping you can help me again.
One of my four albino Corys has been behaving very oddly over the past few days.
He eats normally with the others each morning and swims around a bit but then spends much of the rest of the day lying on his back, appearing to be dead, until he is poked or touched by something. The first time I saw this I thought he was dead but when I went to net him out of the tank he immediately jumped up and started swimming around normally.
Each day since then I have noticed him doing the same thing but as soon as I put the net near him he rights himself and swims away. I saw him do the same thing when he was nudged slightly by another fish.
Is he really sick or is there some other explanation for this weird behaviour? The other three are behaving perfectly normally.
Thanks very much
<Mmm, well, Corydoras can be/act like real clowns at times, but laying on their back or sides is not normal, healthy behavior. I'd look about for an anomaly water quality wise, or at least act proactively and institute a series of daily partial water changes and gravel vacuuming. Bob Fenner>

Extremely lethargic Cory, high nitrates 2/21/11
<Hello Angela>
I wrote about a week ago on another issue, and never received a reply.
<?! We respond to all>
I'm hoping I didn't do anything wrong and my message was just overlooked!
<More likely some "computer glitch"... As the WWM "doorkeeper" ala LeGuin's Earthsea double trilogy, I see, post all>
As it is, that issue seems to have resolved itself for the most part. Now I'm dealing with something in my other tank, and I'm hoping for some insight from more experienced hobbyists than myself.
Tank: 14gal (functionally about 11-12gal with substrate and lowered water level), Aqueon filter that came with the "starter kit", temp steady at 75*F, fully cycled and has been set up since early December 2010. The pH runs pretty steady at around 8.
<For what species of Corydoras? This is too high... I'd mix in some water of lower pH... likely RO>
I always treat new water with Prime.
<Likely not necessary, but...>
Residents: 3 peppered Cory cats, 4 albino Cory cats, 2 juvenile mystery snails. The Corys are being quarantined here, their eventual home is a 55gal. I've had them for about 2 weeks.
Tank stats last night, with API test kit:
Ammonia: 0
NitrItes: 0
NitrAtes: over 80 (YIKES!!!)
<Needs to be addressed... Have you read here: http://wetwebmedia.com/FWSubWebIndex/fwnitrates.htm
and the linked files above?>
I performed my usual 30% water change, all I had time for, with plans to do another this morning.
This morning, I tested again:
Ammonia: 0
NitrItes: 0
Nitrates: over 40, close to 80 on test kit
Performed nearly 70% water change. Retested.
NitrAtes: less than 40, but close
<You need to do something in addition to simple dilution for NO3 here>
Now for the main problem: One of the albino Cory cats has been acting lethargic for the last couple of days, is not eating well, and after last night's water change floated belly-up for a few minutes despite all my attempts to match temperature, etc. with the new water. I was afraid we would lose him, but this morning he's better. Not great, since he's still spending most of his time resting on the bottom or swimming *very* slowly a few inches, but he's not floating. Everyone else in the tank, including a new baby balloon molly that hitchhiked home with the Corys, is acting and looking fine. Even the snails, which I thought would be the first indicators of poor water quality.
<Much more likely due to the vagaries of the water changes>
The only thing that changed recently is my husband taking over morning feedings for both tanks for the last week. I think he's been overfeeding this one, because I don't know what else would have caused such a large nitrAte spike in such a short time. There was a lot of "gunk" when I cleaned the tank, which isn't normal. I've taken over feeding again.
<Ah good>
Most of the reading I've done (Google is my friend, yes?) suggests that nitrAtes aren't *that* toxic over the short term, but these levels are pretty high and I've seen people mention again and again that Cory cats are "sensitive" fish. Could the nitrAtes spike alone be the cause of this little guy's problem?
<Mmm, yes>
If so, will continued water changes and much reduced feeding be enough to resolve it? If not, what else would cause an otherwise healthy-seeming fish to be lethargic and go off its food with no other sign of disease? I'm a loss on this one!
<Please read the above citations>
Thank you so much, I appreciate your willingness to help out newbies like myself with your amazing wealth of experience!
--Angela S.--
P.S. Is it just me, or are Cory cats just the funniest/cutest little fish ever?
<Are indeed comical, and faves. I keep them as well>
I was rolling with laughter after their first "feeding frenzy" over a shrimp pellet!! I'd buy a whole swarm of these guys if I could, but hubby says no room for more aquariums...
<Mmm, maybe... Bob Fenner>
Re: Extremely lethargic Cory, high nitrates 2/21/11

Thank you so much for the reply!
<Welcome Angela>
These are albino and peppered Corys (Corydoras aeneus and Corydoras paleatus). The lethargic one is an albino.
<The C. paleatus need much lower pH... the Albinos may be either C. aeneus or paleatus>
I'm in the middle of Kansas, so our water tends to run hard with a higher pH. Even the "expert" at the local store where I purchased these guys admitted it's hard to keep soft/acidic setups here without a LOT of work, <Not so much... easy to mix some tap w/ some RO... Read here:
and the linked files above>
so I stuck with platies for our main fish. I was told that with careful acclimation the Corys would be ok, and honestly the other 6 look perfectly fine. I'll look into the RO water option, but if I can't get the pH down enough, should I find a new home for these fish?
I'm not sure what I'd replace them with. (My 7yo son wanted a school of glass catfish, but there's no way we'd be able to keep them healthy. The Corys were a compromise, since most other catfish types he liked get too big.)
<There are many tools that can/will help you identify fishes, other aquatic life that enjoys your quality water>
I use the Prime instead of whatever brand dechlorinator came with my starter kit because we have copper piping in my house. I wanted to be extra careful to avoid getting copper in my aquariums and killing snails/fish.
<Real good>
The albino Cory is still alive, but he's pretty much the same as yesterday -- not swimming much, resting on a rock most of the time. I haven't seen him eat. I did one more water change last night, being careful to get the rest of the "gunk" out of the gravel. The nitrates are now reading between 10-20ppm, which is where the tank was before its regular water change the previous week. I'm going to be feeding lightly and testing the nitrates daily for the week, I think. I'll also be buying some more plants soon, so that will probably help a bit.
<Will help>
I read as much as I could about Corys/nitrates/etc. on WWM and the 'net in general before I posted, but I probably missed something. I'll go back and check out the links again. Thank you again for the response!
<Certainly welcome. BobF>

Corydoras shedding slime coats 8/16/11
Hello, about 2 weeks ago my Girlfriend tried to "help" my community tank by pouring about 10X the dosage of Algaefix which is designed to reduce algae,
<Argh! These products are dangerous, even at the right dose, and should NEVER be used, in my opinion. Even if you magically kill all the algae in a tank, if conditions favour algae, it'll be back in weeks. So the art to removing algae is to change the conditions in the aquarium. Typically this involves adding lots of fast-growing plants under suitably bright light, and then installing a few suitable algae-eating animals (Nerite snails are ideal) that will consume any algae that remains.>
however she managed to kill most of my fish and seriously compromising the health of the others. When I discovered the poisoning most of my fish that were still alive were floating at the top, and my Corys were on their sides. I quickly transferred them all to my goldfish tank, and completely drained my community tank and fixed the problem etc etc. The surviving fish are two long fin black skirted tetras, one diamond tetra and two large leopard Corys. The tetras seem to have returned to normal health.
<Sounds a lucky escape for them!>
However, The Corys went through a few days of touch and go, not eating just sitting there etc. One would swim near the top always gulping air, probably because its lungs were seriously damaged.
<Hmm'¦ no, I'd guess the reverse. If excess slime or chemical irritation was affecting its gills, it'll gulp air and absorb oxygen through its gut. That's what these catfish do. It's normal, and once conditions improve, the Corydoras will gulp air less frequently.>
Now a few weeks later they are doing much better, still not as active before the accident, but are eating and moving around more. However they are still lethargic and also I noticed that their slime coats are starting to fall off.
<Are you sure it's mucous and not skin?>
The water conditions are perfect for them and I recently restocked my Corydoras population, 5 leopard Corys and 1 sterbai Cory and they are all in perfect health in perfect water. The water is at a constant 70-72 degrees, about 30 ppm of General Hardness, and 6-7 PH, no nitrates no nitrites and no ammonia. Will the Corys regain previous health over time,
<If they can, yes.>
or do I have to treat them in some way,
or are they on a slow downward spiral to death?
<Likely not.>
Any help or advice or even information will be greatly appreciated.
Thanks for your time, Jesse
<My gut feeling is your fish will be okay, given time. Cheers, Neale.>

Re: (Guppy Stringy Poop) Peppered Corydoras, Other Factors? 1/24/12
Hi Neale. My Peppered Cory passed last night.

<Too bad.>
I had him under 6 months.
<Can live much longer. I have one swimming around that's about 6 years old.>
I understand what you are saying regarding temperature and respiratory distress. I thought if Cory's could tolerate temps up to 77 F, that 78 F would be okay- but you're saying that Peppered Corys require a much lower temperature.
<Require? Well, they're adaptable. But prefer? Yes, coolish sorts of conditions, like you'd offer Platies, Danios and Neons work best; 22-24 C/72-75 F for all these fish is the ideal.>
I noticed other things about my tank though, and would like to throw these ideas out to see if they may be related factors. 1. As a whole my tank does not accumulate a lot of algae. What algae there is, I clean every week to every other week. I have this one fabric plant that I hadn't cleaned in about 3 weeks. I noticed the accumulation on this plant was the color black- I'm assuming algae and tank "muck". It did not clean off well with a brush, so I decided to soak it in a weak bleach solution for 30 minutes. Then I tried scrubbing the plant again, and still the black was difficult to remove- it reminded me of black paint. Could this accumulation be toxic to the fish?
<In and of itself, algae, even Black Beard Algae and Hair Algae, isn't harmful. Bleach could be, of course, and I would never use it. Hydrogen peroxide is a safer bet if you really want to blitz something, but do bear in mind that if something has algae today, and you clean it, it'll likely have algae all over it a week from now. Algae is caused by an environmental problem, and if that problem remains, the algae will be back. Do read:
and the linked articles.>
I do 25% weekly water changes and ammonia and nitrite are zero, nitrates up to 20 ppm. 2. I noticed on the rubber parts of my heater, "red" algae accumulates. Is this harmful? Thank you- Lorie
<Unlikely. But blue-green "algae" (which may be red or black, as well as cyan, blue, green, or purple) is indicative of poor conditions. I've usually seen it in tanks that are overstocked, under-filtered, overfed, or with too little water movement. Blue green algae seems to thrive in regions with poor water flow, and that will likely mean little oxygen, and that in turn is VERY harmful to bottom-dwellers. Reflect, investigate, and act accordingly. Cheers, Neale.>

Eyesight of Corydoras and other advice, env. 4/7/12
Hi there WWM Crew,
Your website has been of great help to me when I had a pair of Bettas. I'd never thought I would actually email you to consult some of your wisdom, but here I am.
I am playing with a self sustaining tank (or partially self sustaining).
Actually let me rephrase that, a self sustaining 1-gallon jar.
In said jar, I have
1 Ramshorn snail,
2 Malaysian trumpet snails (and their various off springs)
1 Corydoras aeneus
<Needs more room, filtration...>
3 ghost shrimp
1 large Anubias plant (not sure of the species)
1 Anubias nana
Some crazy elodea that needs constant pruning
<Likely E. canadiense>
Water wisteria (which is also crazy and needs pruning) Java fern hitch hiker that is now growing daughter plantlets a banana lily which I just de-leafed since it was getting lanky banana lily leaf left floating that is growing roots random strands of java moss that probably hitch hiked on the Anubias Various masses of micro fauna (Cyclops, daphnia, other mini crustaceans, worm and Planaria)
Algae that is constantly being munched on 3 seashells as water buffer
The substrate is about a 1/4-1/2 inch of sand + scattering of gravel.
plants are planted in measuring caps (with holes drilled) and gravel, just to keep it neat.
Tank gets 12 hours of light a day from a 100w cfl that I turn on for all my plants. The larger Anubias is sprouting its third leaf in about 2.5 months, probably due to the bright lighting. There is no filtration or aeration.
The lid is kept on the jar at all times.
I have never measured my water parameters, starting this whole thing of as a simple experiment and really just wanting to keep underwater plants. The tank has not had a water change since its setup at around a month ago, and since the ghost shrimps are going along swimmingly, I will avoid putting a hole in this poor students wallet and forgo test kits for now.
The original inhabitants at the top of the food chain were feeder minnows, all which succumbed to fish tb (apparently a local Petco epidemic in their feeder tanks right now, the feeders have yet to be restocked), I removed all three fish from the system after they began to show symptoms (kinky spine, floating to top, skinny but sill feeding well).
After the minnows went, I noticed that the mini critter population boomed, and figured that I need to re introduce a fish. I researched for a small hardy fish. This turned out to be the bronze Cory cat. I was hesitant to get the Cory cat being afraid that it will become lonely. However at Petco the other day, I saw this little one bumbling about, very active and decided I would give it a try.
After a week, he is absolutely fine and bustling about as usual, his barbels are growing longer! =D . but I noticed that from the time of purchase that he doesn't seem to see me when i put my finger against the glass right in front of him. in fact there is no reaction at all, he will simply continue to do what ever he is doing. I know the glass is clear as the old minnows used to greet me when I came past and excitedly rush up and down the glass for their food. Do you think its possible the fellow is blind?
<Yes... environmental...>
In Petco he was kind of a lonely guy and the only one that explored the entire tank rather than just the bottom. I studied his eyes and they look fine and not cloudy. I also noticed that when i drop in a bit of a sinking wafer for him, he doesn't know its there until he finds it with his snout, even though it should be in his line of vision.
Other than that, he seems a happy fish so far. The system seems to be able to sustain him as of now, I'm going to let it run for another month with just him to see how it handles the eventual waste buildup. If the tank thrives, I will take a risk and get him a friend. If it doesn't I'll invest in a 10gal for him and get a few more Corys.
I would love to hear any extra advice you would have for my tank as well!
<A neat experiment... have a friend in Hawai'i who makes sealed glass spheres... w/ naught but a Neocaridina shrimp, algae and a sprig of gorgonian (and seawater, a bit of air space); and have seen sealed systems over the years>
Thank you for your help!
<I encourage you to write up your spec.s, observations and submit them for publication in pet-fish e- and pulp zines. If you'd like, I will help you to offer the work to editors. Bob Fenner>

Re: Eyesight of Corydoras and other advice     4/10/12
Hi bob!
Sorry for the delayed reply, I was caught up with my small mountain of school work.
One night, as I was pulling an all nighter, I neglectfully left the lamp on the tank for 24 hours. The algae grew as if they were on drugs!
<A clue!>
Other than the plants (especially the Anubias) the rest of the tank cant be happier. The Cory cat wont stop eating! you cannot imagine how fat his little pot belly is right now. Im a little worried he might eat himself to death.
Speaking of my boast about my ghost shrimps surviving on month, one died a few days ago, right next to his newly moulted shell. I couldn't figure out the reason of his death. the shell was completely shed and his body was lying right next to it. I left it in the tank anyway to see how the system will handle a death. I did throw in a long stalk of lucky bamboo to help with the ammonia absorption. No problems so far it seems.
<Mmm, needs to be tested>
I also threw in a piece of banana leaf to see how it will impact the system. Nothing so far other than a mildly yellow colored tank.
Thank you for offering to help me with keeping a diary on this 1gal tank but Im not sure if this crazy schedule of mine will permit any reliable updates :( although I am quite excited about how this little jar is going along.
<Ok; perhaps later>
You never answered my question about the bronze Cory. I am just curious about the overall eyesight of the species and whether its possible that this one is blind? (being unreactive to curious fingers again the glass etc)
<Yes, is possible... from environmental stress... the nutrient levels are likely sky high. I'd check Nitrate... as a window here>
Thanks again for reading!
Here's a couple of photos of the system and its inhabitants.
One of the trumpet snails, see if you can  spot the ghost shrimp!
crazy plant needs pruning
The little guy is taking one of his rare breaks
A week ago
<Thanks for sharing. BobF>
Re: Eyesight of Corydoras and other advice     4/11/12

My goodness, fast reply as usual!
Thanks for the heads up on the nitrates, I've read somewhere that plants absorb nitrates slower than ammonia.
<Ah yes; for the most part, this is so... and not widely understood>
 Didn't pay it much heed since I believed that the excessive amount of plants will nuke all ammonia.
<Mmm, no; not necessarily the case>
 will get the water tested soon (at the LFS)  and update you guys with the readings :) Thanks for the advice! maybe the little tank is in need for a water change!
<"When in doubt, water changes". B>

Yes, a glass jar; sealed

Mysterious Sterbai Corydoras Death -- 09/29/07 Hi, <<Good morning, Katie. Tom here.>> I currently have a 10 gallon aquarium housing 4 rosy barbs, four Sterbai Corydoras, and one Panda Corydoras. Tonight when I came home, one of my four Sterba's had sadly passed away. <<Sorry to hear this.>> None of my fish are showing any signs of sickness and the Cory was alive and well this morning when I went to work. <<Certainly nothing that we like to see, Katie, but, with Corys, this isn't particularly uncommon. Their diminutive sizes along with their normal behavior, i.e. lounging on the bottom of the tank, hiding out under plants/decorations, frequently makes it difficult to 'spot' trouble.>> I have had the tank running for a year and all of the fish are the original inhabitants of the tank (cycled before they moved in), except the Panda Cory which I moved into the tank about a month ago (from another tank in my house, which it had lived in for three months). I have no idea why the Cory died as he looked very healthy up to the point where he was, well, dead. Although none of my Cory's are extremely active like other people mention, they do their share of swimming around or lounging on the driftwood in the aquarium. The tank has about 3 watts per gallon of light, but the tank is planted and covered with so they can hang out away from direct light and the lights are on a twelve hour timer. The substrate is sand with a bit of Fluorite mixed in for the plants. I have noticed on all my Corydoras, the barbels are not entirely developed and shorter than the pictures of the Corydoras I find here. (Could this be because of the Fluorite chunks?) <<I consider the notion that Corys 'wear down' their barbels on certain types of substrates a bit of an 'old-wives' tale', Katie. Barbels, almost invariably, deteriorate due to bacterial infections (much like fin rot), not by being worn away on sharp edges of materials. (How long would you walk, haphazardly, on sharp stones in your bare feet before the 'light bulb' went on? Not long, I'm guessing!)>> I am giving you the stats below with the hope that you can help me explain and prevent further Cory loss. Any info you can give would be greatly appreciated. Thanks, Katie Measurements taken when I spotted the dead Cory: Ammonia: 0 Nitrites: 0 Nitrates: 20 ppm <<A little high here given a planted tank. No cause for alarm, obviously, just a bit surprising to me.>> ph: 8 Temperature: 78 degrees Diet: dry flakes at 12 hour intervals (from fish feeder), sinking shrimp pellets, frozen brine shrimp, frozen blood worms (once weekly) <<All looks/sounds pretty good, Katie. One thing that we haven't touched on is water changes. These are largely responsible for keeping the nitrates in check and, digressing back to your nitrate levels, I'm wondering if these aren't a symptom of a problem. Sand, in particular, can trap tiny particles of food and detritus, leading to the buildup of pockets of gas (hydrogen sulfite) which is produced by the bacteria feeding on the trapped solids. This isn't such a problem, if at all, in tanks containing certain varieties of fish such as Cichlids, as a common example, because they sift through the substrate routinely and allow the gas to be vented before it becomes problematic. Your Corys only superficially scavenge at the bottom, however, so they won't be of much help in 'disturbing' the sand enough to avoid this potential issue. Since I keep a fairly large number of Corys of different varieties myself, I can speak to the concern that a lot of hobbyists may have about vacuuming the little rascals up in a syphon tube during water changes. Mine think it's grand fun to dash around the tube looking for goodies that they couldn't reach themselves until I've stirred things up. (They don't listen very well, either!) The upshot here is that between the plants/roots and nosy little fish, you may not be getting the substrate cleaned up as well as it could be. This, in turn, may be creating a less-than-healthy environment for your Corys. (A rather lengthy ramble over something that I'd have passed off as 'just one of those things' if you hadn't mentioned the shortness of the barbels on the other Corys.) Honestly, I can't tell you that this had anything to do with the death of your Sterbai but I think it's something well-worth addressing where your concerns are involved. Hope this helps. Good luck to you. Tom>>

Sick Cory, env. dis. 12/9/07 Hi crew! <Becky> I am having trouble with my peppered Cory catfish, Spike, and don't know what to do. I have had him over a year, and he has always seemed to have a reddish fin. <Ahh, a sign of something incompatible with this fish and its environment... chemical, physical, social...> But recently, it has gotten bigger and the skin is falling off. I have had this happen in this area before, and have treated it with just Melafix and it has gone away, but always seems to come back. His fin has become obsolete, he can't use it. Other areas of skin on his body seem to be falling off as well. I haven't heard of or seen anything like this. <The clue that the Melafix product had an improving effect leads me to speculate that the water quality is incompatible here. Corydoras live in soft, acidic waters by and large. What is your water like?> I have tried AquariSol and adding a little extra aquarium salt to my tank, <And Callichthyids do NOT like salts in their water...> but they don't work. My other fish in the 10 gal. tank all seem to be ok, except for Spike. <What are the other fish species? This is a very useful clue... as the others likely have dissimilar water quality tolerances> I isolated him in a smaller tank (1 gal) but he acted very weird, so I moved him back into the tank. Any clue what it could be/ what treatments I should use? Thanks, Becky <Please read here: http://wetwebmedia.com/FWSubWebIndex/callcatdisfaq2.htm and the linked files above. Your answers are there. Bob Fenner>
Re: Sick Cory, env. dis.. NealeM addenda to Callichthyid dis., env. 12/9/07
Hi Robert, <Neale> More a bit of information than a correction really. Where you said today that "..Callichthyids do NOT like salts in their water..." that's only true up to a point. <Oh?> It is certainly the case that Corydoras do not come from brackish water. But there are true brackish water Callichthyidae. Hoplosternum littorale actually seems to prefer brackish water, growing more slowly in freshwater than brackish. It tolerates up to 16 ppt.* Unlike Callichthyidae generally, it is absent from soft/acid waters. I only learned about this a year or so ago, so it never made it into the brackish book. Shame, because it strikes me that this hardy and very robust catfish would be a superb addition to tanks with mollies and such. <Mmm, thank you for this> Apparently also thrives perfectly well in polluted, hydrogen sulphide > rich waters where other fish show signs of ill-health. I thought I'd share though. No need to publish this or anything. I happen to revel in these exceptional members of either freshwater or marine families that "break the rules" and do precisely what you'd not expect. I felt you'd be amused, too. Cheers, Neale * See 'Biology' section here for references: http://nis.gsmfc.org/ > nis_factsheet2.php?toc_id=188 <Thanks again. Will accumulate/post. BobF>

Corydoras Concerns... hlth, acclimation... 2/18/08 Hi Crew, <Mike> Thanks in advance for your assistance with my question. WWM is a fantastic forum and reading the Q&As has become one of my regular daily activities. Keep up the great work! <We're trying!> I'm experiencing some problems with some Corydoras I acquired last Friday and am unsure how to proceed. The specs: 10 (U.S.) gallon quarantine tank. PH = 8.0 <Yikes! A bit high for most members of this genus...> NH3=0 NH2=.3 mg/l <Super yikes... very toxic. I'd at least be trading out prepared water, really discounting feeding... Reading on WWM re reduction...> NO3=0 Temperature=79F <Mmmm, what species of Corydoras are these? Some prefer cooler, warmer water...> Filtration = Whisper 10i in-tank filter Sequence of events: 1. 2/9: Tank set up. Water 50/50 from established main display tank and fresh - seeded with a pinch of fish food to start the cycling process <Good> 2. 2/14: Bio-Spira added. <Good> 3. 2/15: Received delivery from Drs. Foster & Smith containing 5 juvenile Carnegiella strigata and 5 juvenile (what were supposed to be) Corydoras trilineatus 4. Acclimated livestock by floating for 45 minutes and 2 hours of gradual addition of tank water to the shipping bags. <Mmm... I should make a few comments here... re measuring for incoming ammonia, pH to some extent... there are other preferred acclimation techniques for situations where animals have been boxed up for hours... vs. short trips from a LFS... Posted on WWM> 5. Upon release into tank noticed one of the Corys was struggling to maintain proper swimming orientation. Observed what I thought to be inflammation of the gills (gills appeared "bruised" reddish/blue) and clamped dorsal fin. Suspected a parasitic or bacterial infection of the gills. <Ahh! Very common... "burn" from the aforementioned accumulated ammonia, rapid change in surrounding water... the pH changing the "format" of the ammonia inside the fishes bodies, being much more toxic> 6. 2/16: Hatchets doing fine and taking food. All Corys foraging for food, but no improvement in the one showing distress. 7. 2/17: Morning: Hatchets doing fine and taking food. 1 Cory dead. 1 Cory showing distress (swimming erratically, struggling to maintain proper orientation, clamped dorsal fin). All surviving Corys displaying apparent gill "bruising" coloration. Researched on FishBase and believe specimens are Corydoras julii not trilineatus (based on spotted vs. reticulated head markings. A gill "bruise" appears to be normal coloration for julii, but not trilineatus). 8. 2/17: Afternoon: Hatchets continue to be doing well. Cory that was showing distress in the morning continued to degrade. Euthanized to end suffering. Surviving 3 Corys beginning to show distress, dorsal fin clamping. I've done a partial water change with water from my display tank (PH=7.3, NH3=0, NH2=0, NO3=0) <Good> reduced the tank temperature to 78 F (FishBase indicates julii likes a slightly cooler environment than trilineatus) and continue to monitor NH2. <Also good> Any idea what might be going on with these poor little guys and/or suggestions what I can do to help them? Thank you very much for you assistance. Mike <I do think they may have just suffered too much "shipping stress" and the mentioned gill burn... I would contact the fine folks at Dr.s F and S with your report, the likely incorrect species ID on their part, and ask for credit/replacement. Bob Fenner>

Have irreparably harmed my Cory? 3-5-09 Hi. I moved some slate from my 20 gallon to my 40 gallon tank last night. Later on, I noticed my 3 Peppered Corydoras were not moving and my smallest was laying on his side. My other 3 Albino Corydoras along with Platy and 2 fry seemed okay. Am and Nitrites 0. I did 40 percent water change prior to bed. Upon waking this morning, all Corydoras were listless and I thought the smallest one was dead at the top stuck in a floating plant. Am and nitrite still 0. I scooped him out and tossed a good foot into a bucket. He wasn't dead. I immediately tossed him back in the tank (so I thought). I went and prepared some water for another change, came back and found him on the side of the tank ( still breathing). I panicked and put him in a bucket with some tank water and a couple drops of Methylene blue and an airstone while I changed the water and added a Eheim liberty 200 filter to further help conditions in the main tank. All the other Corydoras have perked up. The other is back in the tank floating at the top on it's side, it did go back down to the bottom for a few minutes and now it's back up top, barely breathing. I don't want to make the mistake of considering it dead again, but I don't want it to suffer. Should I euthanize this fish? Wait a bit? I feel like I'm in a fish horror story and I'm the bad guy which I guess I am. :( Gina <Hi Gina. Adding Methylene Blue without good reason is never a good idea. If you see unhappy fish, it's almost always an environmental issue, possibly poisoning. The latter is often a problem if you've been doing painting or anything else that releases fumes into the air. Because Corydoras are air-breathers, they're particularly prone to this type of poisoning. Assuming water quality is good, I'd check the temperature, pH, hardness, and that water circulation is adequate (i.e., the filter isn't running slow), and that there's nothing rotting in the tank that could be using up oxygen. Change 50% of the water now, and 50% early the next morning. Essentially try and flush through lots of clean water. Have you added anything new? Plants? Fish? If so, consider Ick and Velvet as possible stowaways, and act accordingly. Corydoras are pretty robust, and I'd not count them out too soon, but do observe closely for the next few hours. A photo would help us identify problems. Cheers, Neale.>

Re: Have irreparably harmed my Cory? 3-5-09-09-09 Hi Neale. The only thing I did was caulk up some holes in my wall a few feet from the tank the Cory is in. I don't know if that factors in. <Hmm... certainly possible if any types of solvent were involved. By default, when doing home repairs nearby your fish, keep windows wide open and a good strong flow of air through the room. Obviously moving the fish to another room is even better, but not always possible.> I've attached a picture, he seems worse today (not attempting to move away). I've done the water changes as instructed and all other fish in that tank seem okay. I did add some rock to the Cory's tank that I had bought for a redo on my 10 gallon tank that was left over. <What kind of rock? Some rocks are safe in fish tanks, but many aren't.> It was in the 10 gallon for a few hours before I moved it. <OK.> I mention the 10 gallon (in a different room) because I woke to find my six new Kuhli Loaches (had about 3 days) were all dead. <Suspect these were in bad shape before purchase: they are VERY underweight. If you look at them, their heads are bigger and thicker than their bodies. Since the skull doesn't shrink with starvation, but the muscles around the body do, this is usually a sign the fish is starving. In fact a healthy Kuhli will have a chunky body and usually a distinct "shoulder" behind the head where its body is obviously more robust that the head. So in this case, you may have come home with weak fish, making things difficult.> I had recently redid the tank for them (rocks, sand). I added a Eheim Aquaball and kept the sponge filter in the tank. When I came home from work last night, one was floating at the top in a plant (usually stays on bottom during day) but eventually moved down. I thought it was because I had put my Betta in with them and he bullied him. So I removed the Betta. <Bettas and Kuhlis normally get along fine.> Then at bedtime, turned off the lights, threw in an algae wafer (new bag bought last night) and checked on them before bed and they were swimming and doing figure eights, very active. Then all dead this morning. Am 0 Nitrites 0 Nitrates 20 PH 6. I've been struggling with low PH and had removed all driftwood from my tanks and all have had several water changes, the PH doesn't seem to be moving. <A sudden pH change certainly can kill fish. Is the pH 6 all the time? Or does it go up and down? If you have a pH of 6, it's likely you have soft water. I'd recommend fixing that by raising the carbonate hardness. Various ways to do that: commercial pH buffers (7.0 would be ideal); adding a small amount of crushed coral to the filter; or adding a 1/4th to 1/2 dose of Rift Valley cichlid salt mix (not normal salt!) to each bucket of water. Do see here: http://www.wetwebmedia.com/FWsubwebindex/fwsoftness.htm Oh, and do make sure you aren't using water from a domestic water softener; that's very bad for fish. Only use drinking-quality water.> I just bought and set up the 40 gallon tank ( I don't know if you remember our conversation last week ) and now I'm thinking of chucking it all except the Betta and a 5 gallon. I don't understand what happened the last couple of days at all and don't want to do anything until I do. <I'm not 100% clear what's going on, though I suspect the sick Corydoras and the dead Kuhli loaches are separate issues. Now, do remember that the bigger the tank, the more stable it will be, so keeping a 40 gallon tank will be miles easier than a 5 gallon, all else being equal. So don't get too disheartened! But please, go slowly, and do feel free to ask as many questions as you want. I think once you understand the issues behind soft water and pH changes, you'll be able to see the dangers you need to avoid. Cheers, Neale.>

Re: Have irreparably harmed my Cory? (RMF, would appreciate input)<<Ok>> 3/9/09 Hi Neale. Thanks for all your help. <Most welcome.> The pH in my 20 gallon tank that has been running for 2.5 months is at 6. I added Seachem's Neutral Regulator with a 25 % water change Sat night and again Sun Morning. It doesn't seem to budge the pH. <Hmm... this is a very low pH for a community tank. While not in itself a disaster provided you stick with soft water fish only, it would be the wrong place to keep hard water fish like livebearers. My gut feeling would be that if you can't beat 'em, join 'em. Choose only fish that will enjoy these conditions.> I'm reluctant to add it directly to the tank as I wanted to raise the pH slowly. <Correct. You should never add these chemicals directly to the tank. Instead, add them to buckets of water. Alter the water in the bucket, and then use it to replace a bucket of old water in the tank. Over the weeks, the aquarium will gradually shift from whatever the conditions are in the aquarium to the conditions you are creating in each bucket of new water.> With the water changes, the pH will move up towards 6.4, but within a few hours drops back to 6 (the lowest my test goes). <Implies a variety of things, though most likely a combination of high stocking (lowers pH via organic acids, nitrate, etc) and lack of carbonate hardness in the water (nothing to inhibit pH decline). Certain materials, notably bogwood, will also lower pH.> I get the same readings and results in the 5 gallon tank that has the Betta. <OK, does sound as if you have very soft water. This is tap water, right? Not from a domestic water softener? You should never use water from the latter.> I purchased one of those test strips for alkalinity. <OK.> Currently in the 20 gallon (which houses 3 Platies, 1 fry, 6 Corydoras (the sick one is swimming around and looking for food a bit now) : pH 6 Hardness 120 (which reads as moderate not soft? Also, I do have build-up around my faucets) <<This could be salts, not of Ca, Mg... not contributing to hardness... RMF>> Alkalinity 0 Nitrite and Nitrate 0 Ammonia 0 My tap water comes out (tested from inside and outside sources, tested immediately after drawn and then after aerated for 24 hours) pH 8 Hardness 120 Alkalinity 120 (sometimes looks more like 180) Ammonia 2 + <<?!. RMF>> Currently in the 40 gallon which was filled with conditioned water, pH 8, 4-5 days ago and has been running with Eheim filtration with temperature set at 80 degrees. The Alkalinity in the 4 days has dropped from 120 (180?) to 80. pH from 8 to 7.6. I added a full dose of Seachem's Regulator on Saturday to this tank. <I'm getting a déjà vu feeling here! For one thing, you're using strips, and these seem to be less reliable than liquid test kits, so if possible have your local aquarium shop test some water and compare it to the results you get. But secondly, there seems to be a thing with the water supplied to some (American?) households where the water chemistry rapidly changes of its own volition within a few days. For whatever reason, it isn't something I've come across in the UK, so can't speak about from personal experience. Essentially it means that there's a combination of additives and minerals in the water that over a few days change sufficiently that water chemistry alters dramatically. Take a look here: http://www.wetwebmedia.com/FWSubWebindex/fwhardnessfaqs.htm Go specifically to the thread "pH/Ammonia Issue (RMF, never come across this, any ideas?)" and you'll see than Bob and I went over and over a similar issue with another a fishkeeper.> <<I have re-read... and have encountered such issues, vacillating GH, KH in tap/mains water supplies... As stated in the cited string above, there are municipalities that at times will run more of a few types of mainly "flocculants" (though other chemicals can/do have this and other "anomalous" effects)... And there are many cases of "bad readings", particularly for strip-type tests... and other endogenous factors can certainly cause wide and rapid shifts in hardness and pH... as is gone over... RMF>> I've read that certain conditioners for chlorine, Chloramine and ammonia will pose false positives for ammonia depending on the test kit used. <Correct. Test the tap water prior to adding anything. Any traces of ammonia will be dealt with via your additives, so shouldn't be an issue.> With Kordon's AmQuel as I can get the ammonia down to 0 for water changes (using twice the dosage amount, but reads for 1 ppm removal, since my tap comes out at 2 ppm, I'm assuming this is correct?). <Can't do any harm.> With Seachem's product, which says it treats for all the same, I can't get the level down to 0, in fact it doesn't budge the ammonia at all. <Your ammonia test kit will detect "false positives" from certain other chemicals, such as Chloramine and apparently Nessler's reagent.> Nor does it seem to adjust the pH based on my drip test (neither on water drawn and conditioned and tested immediately nor tested 24 hours later after being aerated). Another conditioner I tried this weekend will drop the ammonia to .25, but no less, no matter how much I add. Am I over dosing the conditioner? Am I correct to not add any water to my tank unless it reads 0 for ammonia? <<Yes! Best to treat, store "new" water outside the system... for a week if you can. RMF>> Can you best advice on how to stabilize my pH from here? Or ideas on to the cause and/or how to further test to determine what is going on? I've recently upgraded all filtration and moved the biological filtration to the new. However, it seems useless since my pH is so low. <OK, here would be my advice. Put the strip test kit to one side for now. I'm assuming it's an all-in-one strip, right? Let's assume these are mislead/unreliable when used with your tap water. Leave them for checking nitrite/nitrate levels at which they'll be fine and dandy. Good enough for making sure your water changes and filtration are doing their thing! Buy a carbonate hardness test kit and a pH test kit. These are the two critical ones for water chemistry. The general hardness test kit, though it sounds useful, actually has somewhat limited usefulness despite being "general". It doesn't really tell you anything about the ability of water to resist pH changes; only how much non-carbonate "stuff" is in the water. Since these minerals have near-zero impact on pH buffering, this isn't informative. Now, your carbonate hardness kit will test specifically for the carbonate and bicarbonate content of the water, and THIS is the stuff that keeps pH from changing. The aim for most freshwater fishkeeping is get a carbonate hardness of around 5 degrees dH (about 90 mg/l calcium carbonate equivalent). This amount should buffer against any reasonable amount of acidification between weekly water changes. If you find you don't have this amount of carbonate hardness, you'll need to add some to each new bucket of water. A good Malawi Cichlid salt mix will do the trick, though obviously there's no need to use the full dose. The usual ratio is: 1 teaspoon baking soda (sodium bicarbonate) 1 tablespoon Epsom salt (magnesium sulfate) 1 teaspoon marine salt mix (sodium chloride + trace elements) For a Malawi aquarium you'd add this to each 5 gallons/20 litres, but since we likely won't need nearly so much, try using one-fourth the amount to begin with, and if that doesn't work, one-half. So initially, 1/4th a teaspoon of baking soda, 1/4th tablespoon of Epsom salt, 1/4th teaspoon marine salt mix. This is clearly not an expensive way to go! But it works really well, and should fix the pH at around 7.5 plus or minus a little, and get you a carbonate hardness around the level we want. General hardness will be somewhere around 10 degrees dH, but it really doesn't matter that much. Add these salts to buckets of water prior to use, and ideally, leave the water overnight and then test the water chemistry (pH, carbonate hardness) again the first few times, just to see how things pan out. With luck, the Malawi mix will compensate for any funniness in the water as supplied by your water company. Problem solved.> The tanks have river rock, sand, slate, gravel, but nothing that I haven't bought at a LFS. <Cool.> Thanks again for any insight or instruction you can provide. Gina <Hope this helps, Neale.> <<I do agree with your "all fits" advice above... Starting with most any/all source water, the simple mix/addition should serve to bolster hardness, fix pH well enough... RMF>>

Re: Have irreparably harmed my Cory? (RMF, would appreciate input) 3/10/09
Thanks, both of you.
<Most welcome.>
I've treated 5 gallons of tap water with Amquel and 1/4 tsp of each baking soda, Epsom salt and marine salt. I'll let it sit overnight with an airstone before I do a water change.
<Quarter TABLESPOON of Epsom salt! Not teaspoon. No big deal this time around, but try and get it right next time, eh? Oh, by the way, one tablespoon is three teaspoons, so a quarter tablespoon would be 3/4ths of a teaspoon.>
I got a carbonate hardness test as well. I already had liquid tests for pH and all the others. Although the numbers are a bit different, it seems to show the same trend as the strip test.
The 20 and 5 gallon tanks register a pH of 6, 0 mg/l.
<Low; biological filtration operates best around 7.5-8, and below 6 stops altogether. So unless there's a darn good reason, a pH of 7 or slightly above is the ideal for community tanks.>
The 40 gallon tank that was conditioned with Amquel and has been running fishless at 80 degrees with a pinch of food added daily, registers 50 mg/l and a pH of 7.2. This is after 5 days. My tap comes out 90 mg/l and a pH of 8. I have had a bucket of untouched tap water running with an airstone for close to two days and it still has the same readings. So I'm assuming around 4/5 days my carbonate hardness drops by half? I'll guess I'll keep testing the tap water and 40 gallon tank to see how fast it continues to drop.
<If you add the carbonate hardness "recipe" suggested, my prediction will be that water chemistry in terms of pH will remain essentially stable between water changes. The higher the carbonate hardness, the less pH will drop. Hard, alkaline water (like in a hard freshwater aquarium) basically doesn't change at all, or if it does, by tiny amounts. See how the one-fourth dosage I've recommended works out; if it doesn't work, up the dosages to one-half dosages per bucket of water. Even at full dosage, it's would be ideal for things like livebearers, though soft water fish such as tetras might complain.>
I'm assuming I won't see a jump in the pH or carbonate hardness with the Cichlid mix overnight ( in the treated change water) as it takes several days for it to drop.
<Correct. And with increasing carbonate hardness, the rate at which pH drops will slow down.>
Does that mean, it might be several days before I see a change in my 20 gallon tank?
Is a 20% water change with the new mix, every day, too quick a change?
Should I go slower than that?
<This should be fine.>
Also, Bob, had put a ?! next to my tap water ammonia reading of 2+.
<This is for your tap water, right? Before treated with dechlorinator? The _maximum_ allowable level in drinking water is 0.5 mg/l, in the United Kingdom at least. Ammonia usually gets into drinking water via things like agricultural run-off. Do check with your water supplier what the ammonia content of the water supplied to you should be, and ask whether this reading is normal. There could be a problem. If you're detecting the ammonia AFTER adding dechlorinator, you're probably detecting Chloramine after treatment with dechlorinator. Provided the dechlorinator treats Chloramine, you can ignore this "false positive" reading for ammonia.>
It's steadily at 2. Is this abnormal?
<Yes; check with your water supplier.>
I shower in the stuff and my dogs drink it.
<Ammonia isn't especially toxic to humans at low doses (our bodies produce the stuff all the time) but it isn't normal to get this amount in drinking water. If you add water with ammonia at 2.0 mg/l to the aquarium, you're basically dumping a lot of pollution in there. While the filter will fix that problem reasonably quickly, for a short while at least the fish will be exposed to a serious toxin.>
Eventually I would like to store water a week ahead as suggested, I tried it at the beginning of all this but after week the tap water still registered ammonia at 2. But at this point, I've read so much, I feel like I have too much information and not enough understanding.
<<Ahh! A beginning for enlightenment. RMF>>
<The addition of carbonate hardness to each batch of water should make the water chemistry problem go away. Trust me on this. As for the ammonia, that's a weird one. Some products such as Kordon AmQuel will remove ammonia from tap water, making it safe to use. Do see here:
Once your water is hardened and then treated for chlorine, Chloramine and ammonia, it should be ready to use. I can't see any further problems with your fishkeeping, and hope it will be a LOT SIMPLER after this.>
I'll keep you updated on if this works for my system. If it does (fingers crossed) does this mean I should eliminate my Corydoras from my tanks since I am using a salt mixture to steady the chemistry? :(
<Nope. The amount of carbonate hardness is low enough not to bother Corydoras, and the salinity trivially slow. To put this in context, seawater has 35 grammes per litre salt, which is almost 6 teaspoons per litre, or about 22 teaspoons per US gallon. The one-quarter teaspoon is as nothing by comparison.>
Thanks again,
<Cheers, Neale>

Dying Cory cats Hello all, been a while since I've emailed. Thanks for your continued advice. I have a problem with my Julii Corys that has me puzzled. I have a very well established 29 gal tank that I run RO water in since my local water is extremely hard. I have several species of Corys including, until last week, 9 false Julii Corys. The tank is well planted and water conditions are excellent albeit a bit on the acidic side. This never has been a problem and the fish have thrived. However last week I lost two Corys unexpectedly. They each went from perfect to dead very rapidly. I've never seen such healthy-looking dead fish. Similar behavior for both: hovering at the water line making bubbles to exhaustion, then losing balance, then gasping, then dead within a matter of a couple hours. This morning I've noticed a third Cory starting the same pattern. I've done two 50% water changes and added an additional water stone thinking perhaps the O2 content was low given the gasping. I've added some pH stabilizer each day over the last few so now I'm around 6.8. (I usually add some aquarium salt during water changes to augment the RO). Thinking perhaps swim bladder problems but can't imagine why multiple fish affected simultaneously. Any thoughts or suggestions? Appreciate you, Dean <Dean, do please check circulation in the tank. Corydoras are extremely sensitive to poor circulation. While they do gulp air if they need to, they are essentially fish that rely on dissolved oxygen. If you have, for example, a hang-on-the-back filter it is entirely possible that water circulation from the bottom of the tank (where the catfish live) to the top of the tank (where oxygen gets in) is poor. The fact the cats are spending time close to the surface suggests that this is the problem. Also check the substrate is clean (it should be given a bit of a rake through every couple of months, at least) and that the pH is stable between water changes. Another misconception with Corydoras is that they tolerate/prefer warm water. They most certainly do not! The maximum temperature for most species is around 25 C (77 F) if you want them to do well. Ideally, slightly cooler, around 22-24 C (72-75 F). Finally, do spend some time reviewing the basics. If you're adding salt to a freshwater aquarium, you're doing something considered (at best) obsolete and at worst harmful for the last few decades! There's no need to add salt. If you are using RO water, that should only be a portion of the water added to the tank. Unless you are keeping something very specific that needs super-soft water, then a 50/50 mix of RO with hard (non-softened) tap water is perfect. That'll give you a hardness around 10-12 degrees dH, pH 7.5, an absolutely ideal level for Corydoras and a wide range of community tropicals. Very soft water causes all kinds of problems, and for the vast majority of aquarists there are more risks associated with very soft water than benefits. Moreover, adding salt -- by itself at least -- to RO water, and assuming that makes it water acceptable for keeping freshwater fish is not correct. By all means use it dilute the hardness of tap water 50/50, but never, ever keep fish in a 100% RO water, even if you're adding a little salt. Cheers, Neale.>
Re: dying Cory cats
Thanks for the advice Neale, fish seem to be doing well. Appreciate you. <Glad the fish are well, and thanks for the kind words. Cheers, Neale.>

Sterbai Corydoras with White Lump on Nose 4/14/2009
Hi There
Two days ago I discovered that two of my five Sterbai Corydoras had lost their barbells and both have a white lump on the tip of their nose. The lump appears to be solid, see attached pictures.
I've removed them from the community tank and put them into my 25L holding tank. As per the LFS (here in Australia) I have begun treatment with Tri-Sulfa tablets. I've also added an airstone to the tank, in case they need extra oxygen. The other Corys and community fish appear to be fine.
Prior to the Corys getting sick, my community tank details are:
1. Water parameters
Temp: 28C
PH: 6.8
Ammonia: 0
Nitrites: 0
Nitrates: 5
2. Tank set up
Size: L 36' (92cm) X W 14' (36cm) x D 19' (50cm)
Substrate: As seen in above pic, small round smooth gravel
Filtration: Aquaclear 50 (HOB)
Furnishings: 2 logs (aquarium decoration bought at LFS), 2 slate rocks, a terracotta pot, a terracotta plate, 1 large piece of driftwood, 3 Amazon sword plants
Tankmates: 2 Bolivian Rams, 1 SAE, 6 Dwarf Neon Rainbows, 6 Neon Tetras, 9 Ember Tetras
Tank has been established for 11 months.
Does anyone on the Crew know what this is, and have I begun the right treatment?
Thank you in advance for any advice on this matter.
<Deanna, the treatment is very simple. Take out the gravel; put in smooth (not sharp!) silica sand or an aquarium sand expressly suitable for burrowing fish (many aren't, e.g., Tahitian Moon Sand).
What you are describing is extremely common. All that happens is that the Corydoras burrow into the gravel, or try to at least, and they damage their snouts. Bacterial infections set in, and the whiskers rot away. Corydoras shouldn't be kept in tanks with gravel, though a lot of people do so (and yes, they all have Corydoras with missing whiskers). Cheers, Neale.>

Re: Sterbai Corydoras with White Lump on Nose - Follow Up Question 4/14/2009
Thanks for your prompt response Neale. The choice of substrate did cross my mind, and I will change over ASAP. Should I continue with the Triple Sulfa treatment in the quarantine tank because they still have a lump on their nose, or can I move them back to the main tank?
<Hello Deanna. By all means carry on treating against Finrot, but in all likelihood these fish will get better by themselves. So finish the course you've started, but once done, simply wait for the Catfish to heal. Cheers, Neale.>

Albino Catfish?? 6/26/09
I have what I think is an Albino catfish, it hasn't been well for the last 3 weeks now.
<Do you mean an albino Corydoras or an albino Ancistrus Bristlenose catfish?>
For the first week it was "tornadoing" and spinning in circles, couldn't swim straight if he tried.
<Often a sign water quality is seriously bad: check the pH is stable, somewhere between 6 and 8 but not varying much; also check that nitrite level is 0 and ammonia level is 0. Can also occur when water that is too cold (barely above freezing) is added to a tropical tank, or when the water contains some toxin that hasn't be treated with an appropriate water conditioner, such as chlorine, copper or ammonia.>
It didn't seem right to me but I was told this was the nature of the fish to be a little crazy.
Now for about the last 2 weeks it hasn't moved from the bottom of the tank laying on its side.
It is still breathing but doesn't seem able to really move.
<Outlook is grim.>
It seems completely normal in that it isn't bloated or discolored at all, it seems its just gone lame?
<More likely you're doing something wrong (or rather, not doing something right) in terms of maintenance. Let's assume this is a Corydoras catfish.
These are schooling fish, and it's cruel to keep them in groups of less than 5 specimens. They need a reasonable amount of space, 20 gallons or more for a group of 5. They need warmth, but not too much, around 24 C/75 F being ideal. The water should be clean, 0 ammonia and 0 nitrite, and the filter should be working briskly enough that there's a good strong current.
The water used in the tank should have a hardness between 5-20 degrees dH, pH 6-8. You shouldn't be using water from a domestic water softener or heaven forbid de-ionised water by itself. All water should be treated with a dechlorinator before use.>
Any information you can give me would be greatly appreciated.
<Need more information than you've offered, to be honest, so can't help much at all than to suggest what you might be doing wrong.>
Kind Regards,
<Cheers, Neale.>

Sick Corydoras 8/18/09
Hello everyone. I was hoping you could answer a question for me.
<Fire away!>
Today, I noticed one of my Cory cats acting kind of strange. It was kind of flipping out, scratching each gill simultaneously on the substrate while swimming. Seems healthy, swimming normal now. Does not have any marks on him, spots etc. Have you ever seen them do this before?
<Does happen, yes.>
I tried doing a search on your site and did not see anything.
<Do review possibly sources of toxicity: paint fumes, insect sprays, etc.
Corydoras, being air-breathers, are peculiarly sensitive to these things.
Naturally, also review the usual things. You should have 0 ammonia, 0 nitrite, and a steady pH. Catfish are stuck at the bottom of the tank, so poor water circulation is another problem. Corydoras want shallow water (no more than 30 cm deep), low to moderate tropical conditions (22-24 degrees C for most species), and brisk water circulation (around 4-6 times the volume of the tank in turnover per hour).>
I do want to point out that back in June I had a bout with Whitespot
(probably velvet or Ich), which is gone now (had a temp drop and noticed this the next day). Treated with high temp (87 degrees 11 days) , extra salt (11 days), Maracide (10 days) and Melafix (7 days).
<Some medications stress catfish more severely than other fish, and using more than one medication makes things doubly risky. For Ick, the salt/heat protocol is the way to treat catfish.>
I hope this is not making a come back. All fish look fine, except for one neon with a little fin damage.
<Do review water quality; fin damage, i.e., Fin Rot, is a classic symptom of opportunistic bacterial infections.>
Tank - 40 gal, measurements amm - 0 nitrite 0, nitrate 15 to 20, PH 7.4.
I have done 2 - 25 % water changes per week since beginning of June. 2 Aquaclear 50s on tank, so I don't think it is water quality.
Fish - Neon Tetra - 12
Colombian Tetra - 4
<Hyphessobrycon columbianus; a fin-nipping species... could be nipping the Neons, Guppies, etc.>
Bleeding Heart Tetra - 4
Corys - 5
Peacock Gudgeon - 1
L183 Starry Night Pleco - 1
Clown Pleco - 1
Fancy Guppies (male) - 3
Maybe I am being too cautious. I appreciate any input you could give me.
<Cheers, Neale.>

Corydoras with a Possible Problem? Env. -- 08/23/09
Hello Crew -
You have been very helpful to me in the past, and I am hoping that you can help me again. This time, my issue is with some Corydoras catfish. I have three of them in my community tank, along with three platys and three mollies in a 23 gal tank. Two days ago, I woke up to one of my platys laying on the bottom of the tank dead, though she was behaving normally and eating just fine the day before. This upset me a lot, but I scooped her out and proceeded to put the rest of the fish into a bucket temporarily so that I could scrub out their tank since I did not know what had killed her.
<Mmmm... you may have "killed" your biological filter thus>
I scrubbed the tank walls down, vacuumed out the gravel thoroughly, and rinsed and wiped the ornaments thoroughly, paying special attention to the ornament that I found her lying half-against. I even changed the carbon in the filter, just to be safe. I put in my dechlorinator and stress coat (because I ended up changing about half of the water and cleaning the ornaments, and figured the slime coat might be altered some) according to the directions listed on the backs of the bottles. Honestly, I do not know if any of this has to do with the issue I am having, but I wanted to give you as much information as possible.
Yesterday, one of the Corydoras catfish started acting oddly. Usually, all of my Corys stay basically at the bottom, swimming around and foraging, and occasionally come to the top for air and swim right back down, as they should do. But yesterday, this Cory started swimming around close to the top of the tank. Not consistently - he still goes back down to the bottom and stays there most of the time, but I have never known any of my Corys to go to the top for any longer than their little breath-trips before.
Worried that he might have something wrong with him, since the behavior was irregular for him, I took him out, and put him by himself in a goldfish bowl (1.5 gals). I know that is not the best place for him, but I have no other tank to put him in where I can isolate him,
<I would return this fish to the main system. Not likely to live in the bowl, and very unlikely has anything "catching">
and I have been keeping the bowl very clean, and the temperature and pH steady at 78 degrees and 7.4 pH, and I have kept the water level low in there so that there is lots of water surface for him to get air from. I have been feeding him one Hikari Sinking Wafer at morning and night, and he does not seem to be touching them, though he swims around like normal now and does not head for the top as he did in the community tank. And now, back in the community tank, the other two Corys are acting the same way as
he was.
<Yes; environmental>
I have not moved them because I do not think there is room for the other two in the bowl with him. None show signs of any disease I am aware of (Ich, parasites, etc) - no white spots, no clamped fins, and the two in the community tank are eating fine. Is there something wrong with my Corys,
or am I freaking out a little too much?
<The water... system... is almost assuredly "at fault" here.>
And if there is something wrong - what, and what do I do?
<Look into boosting biological filtration. Read here:
and the linked files above till you understand>
Thank you for any answer -
<Welcome. Bob Fenner>

Sick Corydoras Catfish Hi, I have a question about what I think is a sick Corydoras cat fish. I have an eclipse six Marineland aquarium, started it in Oct. 2002. Right now I have 2 white clouds, 2 harlequin Rasboras, and 1 Cory cat. <Corydoras catfish should be kept in groups, and not in tanks this small. Do read here: http://www.wetwebmedia.com/FWSubWebIndex/callichthyids.htm> Everyone was doing great since Nov., but these past two weeks the Cory cat has been swimming erratically, gulping water at the top once a day or so. <His going to the surface to gulp air is normal for Corydoras species. If you have been at home more often than usual lately -- say, due to the winter holidays and time off from work/school -- could it be that you are simply watching the tank more often and thus noticing this behavior that was present all along?> He was fine before, eating every day, and almost never went to top to gulp for air, and would move about bottom. Now he doesn't eat, and he hides out in corner of tank, Very still, alive, but still. <What are you feeding him? These fish need meaty foods twice a day.> I had gotten some plants in from a place called aquabotics.com- <I'm not finding this e-tailer...> and they didn't really last the week- 1 java fern, 1 African bulb lace, and a Boca Carolina plant. I had purchased a live driftwood centerpiece the week before, and no problem. <I am guessing that by "live driftwood" you mean a piece of driftwood covered with plants? Did your Corydoras start acting oddly before or after you added this driftwood?> Only the Cory cat isn't doing well- After a weekly water change I got rid of all plants, and the water is totally clear. I had been using a product called Algone, which takes care of excess nitrite/nitrate and keeps water clean. They have a webpage and a few people I know use the stuff- just put packet in filter. I had some high nitrite/nitrate and used it, from decaying plants, and the tank was clean in a week. <When did you start using the Algone, compared to when the Corydoras started going downhill?> I haven't had any trouble with water in past 2-3 weeks: I have no ammonia readings, 0 on nitrate and nitrite readings. Ph is between 6.8-7.2 but Jersey water is hard. I had readings of 20 or 25 on KH and about 15 on GH. I bought an AquaPharm. tap water system, and now the KH is 11 and GH about 9. Water looks a lot clearer too. <Good> Like I said the other fish are great- but Cory, not so good. I don't know what else to test for. <Check the pH of the water coming out of the tap water purifier.> Is there any chance that the plants somehow affected the cat. <Perhaps not the plants themselves, but something carried in with the plants or driftwood.> Any other tests you can think of- he looks fine, no color change, or Ick or anything I can see. Just sits still and won't eat. I'm worried about him but don't know what else to do. <I would suggest weekly water changes (perhaps a half gallon or a gallon) to keep the water quality high.> thanks a lot Rosa Haritos PS- if he gets over this and is better, do you think it would help to get another Cory to keep him company? the clouds and Rasboras get along great- Or would 6 fish be too much for a 6 gallon tank? <Six fish would be too many for this tank. --Ananda >

Are my Corys stressed? Hi there, I'm new to tropical fish having had a cold water system for a few years. I have a small setup of about 8 (UK) gallons - yes I know it's odd! I'm currently cycling my system with 4 Trilineatus Corys. I've had them for a week now but I'm really worried that they're not happy. They don't stay at the bottom of the tank; they swim in the middle and up and down the sides of the tank and only go to the bottom when they're hungry. Now I've noticed that their gills are going pink. I've done ammonia tests and the levels are 0. What am I doing wrong? I don't want to lose them -they're too cute! Can you help please? Thanks, Sau <Hi Sau, Yes, if you are cycling your tank it is producing Ammonia and then nitrites, both of which are deadly to fish. Cycling means that the nitrogen cycle is establishing itself and producing these wastes. You should be testing for ammonia/nitrites and the final product nitrates. Please read more about the nitrogen cycle at WetWebMedia.com and perform regular water changes to relieve your fish from these wastes. This should help, Craig>
Re: are my Corys stressed?
Hi Craig, Thanks for the advice, I'll get reading. Since last emailing, I've tested for ammonia, nitrite and Ph. Ammonia is 0 and Nitrite 0.1 and Ph is 8.6. Could the alkaline water be bothering them? Their gills are still pink. <These fish are sensitive to hard water. This may be your problem.> I also wonder why they are so jumpy. They flinch and hide every time I lift the hatch to feed them and swim up and down the front of the tank constantly. Do you think they're scared at the moment because there are not many fish in the tank? <No, I suspect nitrites, ammonia if there is nitrite, and also hard water indicated by 8.6pH. I was going to buy two more Corys this weekend so they had a bigger family to shoal with and perhaps not be so scared. Do you think this is a good idea? Thanks for helping, Sau <After addressing the current situation, yes, but I wouldn't until then. Check out http://www.wetwebmedia.com/FWSubWebIndex/callichthyids.htm There is lots of info you need there, especially health, source and water issues. Craig>

Doomed Corydoras Hi WWM crew . . . haven't emailed you in a while (thankfully). My main problem is, that no matter how hard I try, my Cory cats never seem to prosper. It's so frustrating since Corys are my favorite fish. <Mine too> No matter what conditions I keep them in, they eventually die, lose their barbels, or remain stunted (never mature from 1 inch juveniles). I have acquired some beautiful harder-to-get species, such as similis "violet", xinguiensis, caudimaculatus, and trilineateus. I used to have six xinguensis (now five? or four?), and have two similis, caudimaculatus, and Trilineatus each. I assume that it is not for lack of company that they are dying. They seemed to lose their barbels on a Fluorite substrate, so I switched them to a bare-bottom tank. The current tank: 10 gallons, sponge-filtered, a few plastic plants, one female Betta, rather warm (80-82 degrees). Every so often one of them, such as the xingus, will die suddenly. I can transfer them to a currently empty 75 gallon tank . . . I just really really wish to breed them, see them grow up and prosper . . . and live. My problems that I can see is the warm water temp . . . the infrequent feeding . . . and the rather dirty tank bottom. Thanks for your time and info! <Arghhh, your breaking my heart. I love the little guys, their selfless devotion to cleaning your gravel, the way they wink at you when you stare at them long enough, ok I'm done. For starters, what are your water parameters? If you are serious about breeding them you will need to set up a tank for them, and them only. Like you said "warm water temp . . . the infrequent feeding . . . and the rather dirty tank bottom" this will cause problems. 82 is a little high, you will need to vary the temp depending upon the type of Cory, but high 70's is a good starting point. These guys love live worms, I feed mine shrimp/algae wafers and left over frozen food, but I am not trying to breed them. 10gal is a little small, a 20gal long is a good start. With good water quality and good food you should be ok. You might try starting with a more common Cory instead of shelling out the cash for the rare ones. Use the Google search tool on our site and google.com to find more information on Cory care and breeding. Good luck, Gage>
Re: the doomed Corydoras ...
Thanks for the speedy reply! I have a few more questions to clarify, sorry. Will Corys be happy with members of other species? Should I get more of each species? As I said, I have several pairs of different species in my tank. This is because I bought them at a local aquarium society auction. This is great as there are many dedicated Cory breeders who can provide us with many healthy, rarer, and more-or-less cheap (about $3 each) specimens. The 10 gallon was intended to be a quarantine tank, but I don't want to move them to the 75 gallon, as they look so small and delicate. Perhaps I should add a small bio-wheel power filter? (I've got an extra one lying around) My water parameters are: nitrites - 20, and pH 7.8 (with "Amazon" buffer), KH 3, dh 2. My tap water is supposedly very soft, with no fluoride and hardly any (if at all) chlorine/chloramines. One of the perks of living in Hawaii! Of course the water is too warm <If I recall you mentioned your water was around 82, this is not terrible, but I would not go much higher> . . . Well I will do more water changes, feed them twice a day, <They love worms!> add a fan . . . and hopefully see them grow to 2 and 3 inch maturity. Thanks for your help . . . Trisha. <Hey Trisha, great idea with the QT tank, it's the only way to go. I would however add the filter (the more the merrier), and keep up on water changes. Nitrates are really high, they should be around 0 I am guessing that ammonia is high too. How long has the QT tank been set up? Sounds like it is rather new. I would still be sure to use some sort of water conditioner to remove chlorine and chloramines, your Amazon buffer may do this, I am not sure. What other fish do you have in the 75gal? These fish are pretty tough for their size. Corys will get along with other species of Corys, but would be happier with more of the same. In the wild they like to hang out in shoals of about 50, not always easy to recreate in the home aquarium. Gage>

Sick Cory Catfish 7/26/05 Hey gang, I'm back to seek your advice once again. I have three bronze Cory catfish in a 3 gallon quarantine tank. The tank is filtered, unheated (temp 21-23c) and not cycled, but I am doing daily water changes to keep the toxins down. The eventual destination for these fish will be my 10 gallon tank, currently occupied by a male Betta. Anyways, two of these three Corys are doing fine, but the third is ill....fins clamped, listless, and not very interested in food, although he does eat a little. I've had these fish for five days now. I matched pH and temperature when I transferred these fish into the 3 gal. tank; chances of some foreign substance having gotten into the tank or water are minimal. I can't think of anything else I might have done wrong. I guess I'm not looking for a diagnosis, as this fish's behaviour is a symptom of pretty much every disease out there...but is there anything you recommend that might help this little guy? I'm continuing to do my best to provide ideal conditions for this fish, but it doesn't seem to be helping. Thanks in advance for your help! JM < Get a heater and raise the water temp to around 27C and treat with Nitrofuranace, watch for Ich. Keep the water clean and maybe use some softer water until a cure is completed.-Chuck>

Strange problem with new Cory cat 9/11/05 Hello! <Hi there> First, I would like to thank everyone at WWM for the awesome collection of information. The articles are particularly good. I've searched the archived FAQ's and cannot find anything that matches the problem I'm experiencing with a new Corydoras sterbai. I bought three of these little guys almost two weeks ago. They are all approximately 1" in length, and have been adjusting happily in my 10 Gallon quarantine tank. On the ninth day, I noticed one of the new catfish had a white colored blotch between his eyes, approximately 2 mm in diameter. It does not appear to be fungus, as there is nothing fuzzy protruding from the blotch. Nor is it deep, it doesn't appear to make an indentation at all. What really concerns me with this fish are the little nasal "flaps" normally associated with Corydoras catfish. They are now absent from this fish, and the nasal passages appear reddish and inflamed. I inspected these fish prior to purchase, and I am confident all three were intact prior to bringing them home. What can this be? <Common... from rubbing... on the bag in transit, on the glass... in captivity. Happily, most always repairs, grows back> The other two Corydoras are perfectly healthy. There is nothing sharp or abrasive in the QT tank to have inflicted injury, nor could it have been caused by other fish as these three have been in there alone. The QT tank housing them has been cycled for several months, ammonia/nitrite read 0.0, nitrate reads very low, somewhere between 1-3 ppm. To be safe, I moved the two healthy Corydoras to another cycled QT tank today, a smaller 5 gallon rendition. The only thing I have added to help the sick Cory is 4 mg of aquarium salt. I'm afraid to go much over that as Corydoras are not very salt tolerant. <Yes, correct> Wouldn't you know the fish store I purchased these from have a 7 day guarantee? As I said, this problem showed up on the ninth day, so now it's on me to try and help the little guy. The fish is swimming normally. He's always on the move, digging around for food. He ate several thawed bloodworms last night, with a good deal of enthusiasm I might add. And even though his nasal passages seem reddish, he is breathing normally. Any help you could lend on this matter would be much obliged. Many thanks, Brook <Good observations, carefully related. I would not be overly concerned here... the red coloring should abate, and the fish appear more "normal" in time. Bob Fenner>

Injured catfish? Just misplaced, Call. sys. 3/4/06 I have three emerald catfish, two adult mollies, and ten 3-wk-old baby mollies. <The mollies and cats like different water qualities... soft, acidic, warm vs. hard, alkaline, cooler...> A few days ago I noticed that one of my catfish seemed to have injured the side of its face somehow, however now I am concerned it might not be an injury. What used to be a scratch on its face has now turned into a pretty large hole, and now it looks like there is a new surface scratch on the top of its head. I have attached two pictures to give you a better idea (in the second picture, the affected catfish is the one on the right). <Can't make out... much> It is behaving completely normally, and the fish aren't shunning it (as they have done in the past to dying fish in the tank), but although sometimes the hole seems to be improving, overall it is getting worse. Also, today the catfish has changed color to a more pinkish/purple rather than green/gold. This isn't just confined to the face or to the fins, but is an overall color change. Also, I haven't seen the babies or any other fish bothering the catfish, although the new scratch looks like something could be bothering it. <Likely not the mollies> I don't have a fully functional quarantine tank. Just a smaller tank without a filter or heater. Do you have any advice on what actions I could take to help my fish heal? Thank you. <Mmm, if you have another tank, place these catfish in it, and change the water chemistry (slowly) to their liking... this will likely "do it". See WWM, fishbase.org re the species habitats. Bob Fenner>

Cory catfish tail & fin disappearing... tiny system, no info. on upkeep or water quality 4/14/06 My son has a 3 gallon Eclipse tank that's approx. 2 yrs old. Originally he had 3 fish, one of which was a Cory catfish. Not sure what the others are. All was well for over a year, then the Cory's fin and tail started disappearing. <... Likely environmental... the tank has gone "acidic" with being small, lack of regular maintenance> Spoke to the fish store & they suggested treating the tank with a green medicine. <No... likely Malachite... too toxic and inappropriate...> Did this 2 different times with no improvement to the Cory, and he died after a month or so. <Poisoned> Got another Cory, <...> and this one started losing his fin & tail almost immediately. Treated the tank again with no success, and started wondering if one of the other fish was eating him. (Never saw any aggression.) Got a tank separator (mesh) and have kept him separate for 2 weeks now. Fin & tail don't seem any worse, but no better either. Fish store suggested feeding him a pellet 2x/week. Doesn't seem to like it, and after a few days it gets fuzzy and floats to the top. Just did a water change and the pellet remains stank horribly. Help!! What's wrong with his fin & tail, and what should I feed him? Thanks! <... What re your water quality? Do you change out water on a regular basis? Perhaps a video fish tank would be better, instead? Bob Fenner>
Re: Cory catfish tail & fin disappearing - 04/14/2006
I do a water change weekly, replacing half the water in the tank, as suggested by my pet store (NOT Wal-Mart). <Good> NO, I'm not a fish expert, which is why I'm asking for help. Could do without smart-aleck comments like suggesting a video fish tank! <Mmm, not for you, but your child. Something is still off, and easily so in such a small volume, with your water quality here most likely. BobF>

Cory Cats With Problems 11/01/06 Hello, I have two problems, but I think they're related. I posted about this in the freshwater aquarium thread and the 911 thread when a second, more serious problem occurred. No one has been able to figure out what this is, so I thought I'd ask you as well. I'll give you as much information as possible. I have 3 tanks: 10 gal: (cycled) 4 three-line Corydoras 1 sunset platy 1 fancy guppy 5 gal: (cycled) 1 male Betta 5 gal QT tank: (not cycled) 1 yellow guppy 5 molly fry It all began with the QT tank. I had originally bought a female black molly and a male yellow guppy. After a week in the QT tank, the molly suddenly gave birth (I didn't know she was pregnant, but I've had platy and guppy fry before) to 6 fry. The following morning, I found the molly dead (Oct 8). While removing her, I noticed that her underside, on her belly, was white. It did not look cottony, like fungus. It was very hard to tell what it was. By Oct 13, I noticed that the fry had white on their bellies also. Since they're fry and so small, it was very hard to identify. Upon closer examination, it seemed gray, like their scales had come off or lost color. It didn't look like something "on" the fish. It was also shiny. It was only on the molly fry. The yellow guppy showed no symptoms. On Oct 13, I did something monumentally stupid and that was change the filter. I had originally taken the filter from my Betta tank (he needed a new one) and used it in the QT tank to cycle it. After putting in the new filter in the QT tank, I realized that I had just killed my cycle, since there hadn't been enough time for bacteria to grow in the tank. I began to do frequent water changes on the QT tank, and I also treated the tank with 3 tbsp of non-iodized salt in order to help with their problem. The fry were eating well, and swimming around, along with the guppy. On Oct 16, one of the fry died. During this time, the yellow guppy began to have red gills, and was hanging at the surface of the tank, and swimming around like crazy. I wasn't sure if he had an illness or was just reacting to the ammonia (which I kept down to .5 or less as well as I could with water changes). Since I wasn't sure, I decided to wait to see what happened while continuing to keep the same level of salt and frequent water changes. On Oct 24 I noticed my Betta had fin rot. I added 2 tsp of salt to his tank and did frequent water changes to keep his water as pristine as possible. I had been doing weekly 40% water changes on his tank, and it was fully cycled, so I'm not sure how he developed fin rot. I had used the same equipment from the QT tank to do his water changes on Oct 10 and Oct 19. I'm not sure if I infected him with the equipment, or if the fin rot developed on its own. Using the same equipment again, I did my regular water changes on my 10 gal on Oct 10, Oct 19, and Oct 29. Between Oct 29 and Oct 31, I noticed that one of my Corys was hiding out (none of my Corys hide, so this was unusual). Also, their gills seemed to be red. Now my Corys had originally had red gills (when I added them a few months ago, I didn't have a QT tank and learned my lesson) and pinkish faces, so I did frequent water changes in an effort to help them battle whatever it was (I thought it may be septicemia). The pinkishness went away, and so did the redness in their gills. On Oct 31, last night, one of my Corys (I'm assuming it's the one who had been hiding before, but I can't tell my Corys apart) began to be unable to swim. He would lie on the bottom, gasping, and then try to swim. He'd tilt to one side and end up swimming in a circle. I immediately tested the water, and my readings were 0 ppm ammonia, 0 ppm nitrites, 5 ppm nitrates. Nothing had been changed to the tank in months, with the exception of using the QT equipment (buckets, cup, gravel vacuum) to do their regular water change. The Cory would occasionally get a burst of energy and begin swimming around frantically, careening into the decoration, the gravel, or the fake plants. As he swam, he'd spin like a spiral football. It was really hard to see my Cory like this, and I assumed I infected my 10gal with whatever is in my QT tank. The red gills and gasping led me to think it was a bacterial infection, so I treated the tank last night with Maracyn. Since my Qt tank is occupied, I had no where to put the sick Cory so was forced to treat him with the others. I also treated the QT tank, since 3-4 weeks of salt has not been helping them at all. I fully expected to wake up this morning to him being dead. Instead, he's still alive, still unable to swim properly, and is lying in my tank gasping for air. I keep checking on him to make sure he is still alive. Two of my other Corys are now hiding out, but I don't know if it's in response to the Maracyn or if they're also beginning to catch whatever the sick Cory has. I'm worried that I might end up losing all of my Corys. Do you have any idea what this is? Will my spinning Cory recover, or should I put him down? < The Cory probably gas an internal infection. Place him in the QT tank and treat with Metronidazole and Nitrofurazone or Clout.> I don't want to see him suffer, but I don't want to prematurely end his life if he can get over this. If I do need to put him down, what is the best method? < Place the fish in a glass of aquarium water and add a couple Alka -Seltzer tablets. The CO2 will remove the oxygen from the water and the fish will go to sleep and die.> I don't think I'd be able to sever his spine, so the least traumatic method for both of us would be best. I'm going to sterilize the equipment by using boiling water (is this the correct method)? < Probably not needed. The bloat is caused by stress. Check the aquarium for uneaten /rotting food.> Should I continue to treat with Maracyn, and how do I do water changes while medicating if it kills my cycle (which I'm assuming it will)? < If you must treat in the main tank then do a 50% water change, vacuum the gravel and clean the filter. After treatment then add Bio-Spira from Marineland to get the bacteria re-established.> I hope this was clear enough for you. I also hope I haven't made the situation worse by medicating with Maracyn, but I've read conflicting information on Corys and salt and didn't want to risk it by using that instead. Any help would be greatly appreciated!-Michelle < Stop using salt with the Cory cats. The really don't like it.-Chuck>

Peppered catfish - more information needed 11/15/06 Hi, <Hello> I have a peppered catfish and he is in trouble. He is lying on the bottom of the tank, sometimes he goes for a frenzied swim but can't go far then floats to the bottom of the tank and he is breathing rapidly. The other fish are fine; should I quarantine him? and can I more importantly save him? He is so cute I don't want to lose him. If you can help I would greatly appreciate it. <A little bit more information about the tank (size, how long its been running, other inhabitants, water change schedule, etc.) and the water conditions (levels of ammonia, nitrite, nitrate, pH reading, temp., etc.) are needed in order to give a proper diagnosis. In the meantime, yes, I would definitely quarantine this fish and keep a very close eye on him. With regards to the rapid breathing, I suspect toxins in the water - do test for ammonia, nitrite, nitrates, etc. and perform a water change if needed. Tanya. <Best regards, Jorie>

Corydoras standing upright on bottom 9/20/06 Hi there, I've been reading your board for a long time now, <Bet you I've been t/here longer> and have learned so much, <Me too> and I now have reason to contact you for the first time. <Good> I recently rescued 2 Corys from someone on Craigslist.org. (I believe the are Corydoras leucomelas) Had them for 2weeks so far. They were sold to the guy I got them from as Corydoras schwartzi, which they are not (these have a lot of black on the top fin) I plan on getting more of them, once these 2 are healthy and get out of QT. I believe that they lived in some very bad conditions before I got them, as they have no barbels. <Yikes... very bad> I'm feeding them live blackworms, and shrimp pellets. One of the Corys is eating well and regrowing the barbels already, but the other one isn't eating as much, and is acting a bit strange. It sometimes stands upright on the bottom of the tank. It will lay on the bottom, then it's head will slowly start to rise, until it's almost vertical. Sometimes it's head stays on the bottom, and sometimes rests at 45 deg. <Very bad> This Cory can swim fine, up and down, swims right side up, but it's not eating as much as the other. These 2 Corys swim together all the time. <This genus are very social animals> I haven't seen the vertical one poop yet, while I have seen the other one doing his business at least 2 times ( but the healthy one is a little piggy) I am thinking constipation or a swim bladder issue? It is not swollen, or bloated in any way. <Mmm, likely just so far beaten down, is having a hard time recovering its health> I just need some advice on what to do now, medicate, fasting...what? <I might try adjusting your water quality (pH, hardness, temp.) more to their suiting... but otherwise would just keep doing what you're doing> Thanks so much, as I want my lil rescued guys to get healthy again if they can. Jay Vance <I wish you life. Bob Fenner>
Re: Corydoras standing upright on bottom 9/21/06
Hey Bob, Thanks so much for your speedy reply. It is so neat to see your responses (< >) in the body of my message, like all the ones I've read for so long on the wet web. <Ahh!> As for their water parameters, and ph and the like, I have them in an 5 gallon uncycled (weekly or less water change) QT, with a ph of 6.8 and temp around 78. <Better to be in an established cycled system. These cats likely have nothing that is "catching"> I have pretty soft water, KH of 1-2, and since I read that these Corydoras leucomelas live in blackwater (from planet catfish's species sheet) I assume that this would be to their liking? <Yes> As for being "beaten down" do you mean that the vertical and 45 deg positioning is from exhaustion/ ill health and possible lack of control of it's swim bladder, but not necessarily an infection or anything else? <Oh! Was referring to the effects of their previous care> That would make me feel better, as I wouldn't want to medicate without good reason. This is what happens when one rescues unhealthy fish, I guess. Time and good water and good food is all I can do, the rest is up to the fish. <Yes, we are in agreement> One last thing, How long should I keep them in QT, under these circumstances, as they have a big 29 gallon planted tank waiting for them, with only 4 Otos in it. They've been in QT for 2.5 weeks so far. Thanks so much again for all your good work. Jay <I would move these Corys to the main tank now. Bob Fenner>
Re: Corydoras standing upright on bottom 9/23/06
Hey Bob, So sorry I'm having to write you again, as I know you're very busy. I believe I've found a big problem that I overlooked before. This Cory has no mouth hole. or a tiny, tiny hole) It sounds strange, but it appears to have been slowly sealed with scar tissue from the barbel burning off issue, from the previous owners tank. The other Cory does not have this problem, and has a normal mouth. This explains why this fish has been not able to suck in any blackworms during feeding, just nosing the ground, without sucking anything up. I can see it's jaw moving, but there is no opening in the mouth skin. In turn, it's breathing is a bit labored, and I see it trying to do a yawn, to open/stretch it's mouth skin. I don't want to do this, but I feel as I'm going to have to do something for this fish. I am very good with my hands, I was thinking of using some very small very sharp sterile scissors, and opening the mouth a bit to allow it to circulate water over the gills and to eat. Do you have any suggestions to me as to minimize stress on the fish, and stopping any bleeding/infection/ other problem related to this surgery? Thanks so much. Jay <I would hold off on trying this surgery... better to hope for some sort of self-repair in my estimation. Bob Fenner>
Re: Corydoras standing upright on bottom 11/4/06
Hey Bob, Here's a quick update. Since moving the QT'd Corys into my 29 gallon planted tank (0 ammonia 0 nitrite 0 nitrate due to pressurized co2 and lots of plants), they are both acting normally, and their barbels continue to regrow. <A good sign> I still can't see the opening on the tiny mouthed Cory, but it has had a full regrowth of it's barbels. All of the scary behaviors have stopped, and they are eating like pigs. <A very good sign> I just wanted to thank you for your help. Even when things look very bad, I guess clean water and good food can go a long way to let these little guys heal themselves.... Thanks again! Jay <Thank you for this update. Bob Fenner>

Aquarium problems, FW, env. 1/11/07 I have a ten gallon tank running for the past three months and have lost eight guppies in the course of a month. <From?> My ammonia and nitrate levels are at 0 and my ph is 7.0 I change my water and vacuum once a week. Since the loss of my fish I have started changing the water and vacuuming the gravel twice a week. <I'd reduce this to just once per week... What is it you're attempting to accomplish by more frequent changing?> My Cory catfish is not doing well now. I have one guppy left and him in my 10 gallon. The catfish is laying on his side and breathing heavy. He has no spots on his body and was eating yesterday. Don't know what I am doing wrong with this tank. Please help. <... Please read here: http://wetwebmedia.com/FWSubWebIndex/fwmaint.htm and the linked files above... I suspect you have fallen into the "cleanliness is sterility" mind-frame... Not valid. Bob Fenner> Lynda Williams

Re: FW high pH, Corydoras beh... need to find, match in the FW Dailies 1/12/06 Thanks for the speedy reply, but have another question. <... please include prev. corr....> You said the PH of 8.0 was a bit high, but its constant and never shifts. Should I alter it a bit lower with chemicals? <Possibly... I would just mix in some water (reverse osmosis likely) that has less/no alkaline component to dilute, lower the pH> Just mix in chemicals in the storage water of 7.0 PH and pour in to the tank? <No... need to allow such pre-made water to set for a few days> Also you think the high PH contributes to the Corys being pale? <Yes, could very likely do so> Thanks for your time, patience <Do take a read: http://wetwebmedia.com/FWSubWebIndex/fwph,alk.htm and the linked files above where you lead yourself. Bob Fenner>

Dying Cory? 4/15/07 Hi.. <Hello> I have two Corys, Pleco, clown loach, three Danios in a 27 gal. tank. all water levels are normal, except that the water does test a bit hard. <... need the actual test values... can't read minds to discern what you mean by "normal"> two days ago I noticed that one of the Corys started leaning against rocks and the tank to hold itself up in a resting position. over the last two days he has become completely motionless and is not eating. he seems to breathe heavily from time to time and at others I wonder if he's kicked the bucket. There is no visible infection on him, he looks fine from the outside, although I think today he got a bit bloated. I have no idea what might have caused his condition or what to do. any advice is greatly appreciated. best, Nathalia. <Perhaps high nitrate, other metabolite/s... water changes... Do please read here: http://wetwebmedia.com/FWSubWebIndex/armcatdisfaqs.htm and the linked files above. Bob Fenner>
Re: dying Cory?
4/15/07 Nitrates are at 40, <Yikes!!! Way too high... by more than twice!> nitrites approaching .5, <Toxic... must be zero, zip, zilch> ph 7.2, alkaline 120 I did a water change yesterday, do so about every two weeks, have live plants, carbon filter, don't know what else to do to bring the nitrate/nitrite level down. <Posted...> Cory passed away overnight. I had him for close to two years, not sure what happened. He had no visible signs of infection. <... Environment...> thanks for the link and writing back. <Please read, learn to/use WWM... the indices, search tool: http://wetwebmedia.com/FWSubWebIndex/fwsubwebindex.htm the link to FW Maint., Water Quality... Nitrates... Bob Fenner>

Cory cat behavior or disease - 05/01/07 Dear crew, Tank specs: 10 gallon, heated to 79 degrees (with a heater that wont stay attached to the side of the aquarium, driving me crazy and always having the tip touching the gravel*. is this a problem?), <No> filtered with a hang-on filter rated for 5-15 gallons, ammonia 0, nitrite 0, nitrate 5 30 minutes before weekly maintenance which consists of a 20% water change, quite often twice a week, a swish of the filter in aquarium water or a change if needed, hand picking of algae <Shouldn't have much of this...> and an occasional swish of the sponge media when theres too much algae. Eco-complete substrate, java moss, a planted plant I cant remember the name of and a floating Anacharis that tends to tip more then it floats. One small lace rock. <I'd pull this... soak in some warm/boiled water... test the water for phosphate... may be a principal contributor to your algae growth...> Plant light florescent for the lighting, on about 12 hours a day. Two panda Cory cats, two albino Cory cats, a male Betta and lots of pond snails (that I purposefully introduced*. I like them). Feeding twice a day with tropical flakes for the Betta, shrimp pellets for the Corys, frozen white worm larvae, frozen daphnia and Brine Shrimp Directs Beef heart Plus flakes for all. (My Corys LOVE the beef heart flakes.) Feeding is switched up every day, one thing at a time, so no, Im not feeding everything all at once. They fast one day a week as well as fasting my plants one day every two weeks or so (which has done wonders for algae control). <Mmm...> The tanks been set up for a couple of months with fish just being added in the last month or two. No quarantine as the place we bought the Corys quarantines and the Betta was added first. Whew! I hope thats all the information you need. My problem resides with my Corys. First, I was told they would school together, which they dont. The pandas live under the heater and the albinos swim around. I would like to get more of each to complete the school. How many Corys could I comfortably fit in the 10 gallon? <Well... I'd rather that you had just five or so of one species...> We have two other larger tanks that I could move either school of Corys in if theres not enough room to complete the schools in the 10 gallon. <Oh! Good... small, odd numbers of this genus are best in most hobbyist settings... One species if the systems are small...> Second problem. I used to have a fifth Cory cat, albino. Two weeks ago he became paler then the other albinos, no pink cast to his body. He would still scrounge around for food when I fed them. (I feed them at the same time in the same place every time. Even the Panda cats know when to come out.) But other then that, he appeared rather listless. He would even waft in the current and tip a bit. But when I bumped him or another fish bumped him, he would move a little. However, I happened to be leaving that day for a five day vacation and worried that he would die while I was gone and rot in my tank, causing havoc to everything else, I froze him. Now one of my other Cory cats, who used to be active and pinkish, is acting the same way. He acts more active when hes scared into moving, but other then that, he just sits around, blinking, with not much gill movement (though I know theyre labyrinth breathers, <Yes... of a sort... facultative...> so I dont know whether this has much to do with it). I watched him eat last night, so I know hes still doing that. This has been going on for 3-4 days now with no further deterioration of his condition. So now I wonder, is he sick or did I freeze my last Cory cat unnecessarily? <Maybe> There are no other physical signs of illness that I have noticed besides what is described above. I sincerely hope that I havent just missed the answer in the FAQ section. I have read through the catfish behavior and disease three times and Googled different terms related. I hope I havent wasted your time. Thank you again for your help. Celeste <Thank you for your thoughtful, well-worded questions, comments... I would move the non-Panda species here... and keep it/them in a bit cooler water temp. wise... Do please see WWM, Fishbase.org re the water quality of these species in the wild... Is your water particularly hard, alkaline? Lastly, a cursory note re nitrogenous et al. waste accumulation and these (and most Amazonian) fishes... They do appear ataxic (disoriented) as you note, under such influences... better to have larger volumes, well filtered, maintained to avoid such poisoning. Bob Fenner>
Re: Cory cat behavior or disease 5/2/07
Bob, <Celeste> Thank you for your prompt reply. I must admit in my Wet Web Media addiction I was rather worried when daily FAQ's weren't updated at all this weekend. <Heeee! Glad you noticed> I'm glad to see you alive and well. I hope that going from Hawaii to Canada wasn't too much of a shock. <A bit sleepy... well, sleepier... but many nice folks about, good things to do... Fab meals and drinkies> I can only imagine how much (volunteer) time you spend on this website daily. <A few to quite a few hours... are you able, ready, willing to join us... Yet?> I really appreciate the value you, as well as the other volunteers, bring to this hobby. <Thank you my/our friend> The Albino Cory Cat wasn't doing as well this morning. He was sideways under a plant and didn't come when I fed them. It wasn't until a few minutes later when I swished the plant a bit that he righted himself and started swimming around. After receiving your email, I called my husband and had him move the two Albinos into our Tetra tank. That tank is a degree or two cooler and softer then the water in my tank, has been set up for over 6 months and is 37 gallons. <Good> I've never tested the 10 gallon tank hardness, honestly. I use half filtered tap water that has the chlorine, etc. removed but leaves the minerals in and half RO water. The tap has a hardness of 11 or 12 while the RO has a hardness of between 0-1. I estimate that it is about 6 or 7. I will check tonight. <Also good... often there are other sources (gravel, decor...) that can/do add to hardness...> But I know that the Tetra tank is between 4-5 with a Ph below 7.0. (My husband is in charge of testing the other tanks so I don't know the exact numbers. I just know that we've reached our target numbers for that tank.) Next time we're at the good LFS, we'll pick up more of both types of Corys. <Sounds good> In the 37 gallon, we have 2 ADFs, 10 Neon Tetras, 5 Flame Rios Tetras and 6 Red Eye Tetras. (Now I'm all paranoid and confused about my capitalization after today's daily FAQs.) <Heeee! No worries... missals w/ only a scattering of errors I pick up, mostly through the software...> Someone at the LFS (not the good one, the one that advised me to put 2-3 goldfish in the 10 gallon with my Betta.... obviously, I didn't) told me that bottom dwellers don't factor into the inch per gallon rule, that's it's more a psychological thing. <Mmm, not so> I could therefore leave the ADFs (and at the time, 3 Loaches) out of the equation when stocking my tank. But I have not been able to find anything to substantiate that claim. <There is naught> I can't imagine that I could have 37 inches in the water and 37 inches on the bottom, especially since Cory Cats are probably messier then, say, the ADFs. How many Cory's could I have in this tank? <Mmm... depending on species, perhaps 15...> I have to admit I fell in love with the school of Panda Cat's at the LFS with about 50 of them. There's just something about seeing them swim together that makes them that much cuter. <Yes> Last thing, I promise. I thought we had done our research on lace rock before we bought them but apparently not after Googling it on WWM this morning. There's some in all three tanks. We have algae in all of our tanks, though it's not the slimy type (BGA) but the course, thick stringy kind that comes out fairly easy. The tetra tank is the worst and that's had the lace rock the longest. My husband pulled the rock out this morning. Phosphate testing kits are not easily found here and we may have to order one. We thought the algae was an over-feeding problem and would straighten out once we separated the live bearers into their own tanks (which we did two months ago). I am slightly confused about your instructions to place them in warm/boiling water. Will this remove the phosphates in the rock? <Mmm, only to an extent... removing the more easily soluble source near the surface... in time, the deeper, more concentrated layers become exposed...> We boiled all the rock before placing them in the tank, but would further boiling help with the phosphates if there are any? <Only temporarily> Or should we just leave them out and find something else to decorate? <Is one approach... Using more (i.e. purposeful photosynthetic growth), utilizing chemical filtrants, limiting other essential nutrients... are others> Thank you again, Celeste <Welcome my friend. Thank you for writing so well, clearly. Bob Fenner>
Re: Cory cat behavior or disease 5/4/07
Bob, <Celeste> We unfortunately lost the Cory Cat last night. Water hardness tested at 8 with Ph at 7.4, which is higher on both accounts then I thought. (Ah, the importance of frequent testing.) According to fishbase.org, that's within acceptable range, but I would like to see it lower then that. <Mmm, yes> I did a 20% water change last night using only RO, and will continue to do so until dH is 6 and Ph below 7.0. <Good> (The Tetra tank where I moved the Albinos is dH - 5, Ph - 6.4.) We plan on buying 10 more Albino Corys and 3 more Panda Corys this weekend. (Well, probably just 4 Albinos this weekend and 6 next weekend....keeping them odd and letting the bacteria catch up.) Well, thank you for asking about joining the crew! I do have the time and I am very willing, however, I've only technically been part of the hobby for 6 months. (Though I grew up with a freshwater tank in my house, I only did water changes and the like when it was my chore.) As a self-proclaimed researchaholic, I know quite a bit about the things I've dealt with (plants, DIY CO2, setup, cycling, Ick, Guppies, Tetras, Loaches, Bettas and Cory Cats, those kind of things), but only general things about other aspects of freshwater and next to nothing about marine. You guys have done enough for me, if I can return the favor in anyway, I would happily do so. Celeste <Your writing displays a keen intellect, capacity for communication, deep involvement and awareness in life. I look forward to when you will feel more comfortable responding to folks here... Even "just" with freshwater queries. Bob Fenner>

Cory problem, no useful data 5/25/07 Hello! I have a Cory...sorry I don't know which kind, but a fairly common one. Recently I noticed that just about his entire mouth has disappeared! The barbels and what I call the snout. There's nothing left but a tiny hole and I don't know if he is eating through that. <Have seen this before... sometimes from collateral shipping damage... on occasion from sharp gravel, other objects in a tank... Can be caused by being attacked, or even consequent bacterial infection... from something/s amiss in the way of water quality> He's certainly not as active, but is not showing any other signs of fungus or infection. Gills look fine. Must be losing weight. What is the prognosis? Will his barbels and snout grow back? <Might, depending on how damaged, the root cause/s...> How can I help him because he's so sweet. I have already set him up in a hospital tank. I put Methylene Blue in his water. Thanks so much...I really want to save him! Elise <... Need to know what the system consists of, maintenance, water quality, foods/feeding... Even tankmate species... Can't guess w/ what little you've provided here. Bob Fenner>

My poor catfish!! Corydoras dis., use 8/22/07 Good morning, we are fairly new aquarium owners, we have 2 gravel cleaner Corydoras and one of them has a very swollen belly, we thought it might be pregnant but today it is finding it very difficult to swim and keeps going to the surface. Sometimes it falls back down to the bottom like its dead but then will swim back up. Not keeping it's balance very well. The other one looks fine and is sat on the bottom as normal. Please could you give me some advice on what to do. I can't seem to get a clear enough picture but will try if you really need one. They are a grey colour with a pinkish tone, about 2 inches long. Thank you so much Sharon <Hello Sharon. Corydoras aren't "gravel cleaners" -- that's your job. Indeed, forcing catfish of any kind to root about dirty gravel causes infections to set in, typically associated with eroded barbels (whiskers) and, in serious cases, reddish sores on the belly. A photograph will help, but my assumption without one is that your catfish are suffering from poor water quality. In a new aquarium the ammonia and nitrite levels quickly reach toxic levels. Catfish will try and mitigate the problems by gulping air, which is the dash to the surface your catfish are doing, but eventually the ammonia and nitrite cause damage to the fish, which is the odd behaviour. Even in the short term, prolonged exposure to nitrite and ammonia will kill them. Using your test kits (which I hope you have!) ensure the ammonia is 0 and the nitrite is 0. If this is not the case, do a 50% water change. Repeat the water test and, if required, 50% water change every single day until you get 0 ammonia and nitrite for two or three days on the trot. At that point, you can scale things back to 50% water changes per week. Cheers, Neale>
Re: my poor catfish!! 8/22/07
Thanks for the reply, the poorly one has got a red sore on his belly. The other one is fine, sorry about the gravel cleaner thing, that's what we were told at the shop we bought them in and we certainly don't force them to feed from the bottom and we clean the gravel with a suction thing (haven't quite got the hang of that task properly yet!!) Can't get a decent photo as he is laying on his back at the back of the tank but is still moving. Water test levels are as follows ammonia and nitrite are at 0ppm ph levels are slightly high at 7.4 and nitrate is in between 0 and 5 ppm. Tank is about 3 months old now and we have a variety of fish including mollies, tetras, a Betta, Plecos, silver shark, clown loaches and one of our guppies has just given birth to 18 fry ( which are in a nursery tank) all other fish are fine we have only lost two Tetras (one zebra tailed and one gold) since we started. Thanks Sharon <Water chemistry/quality sounds fine. pH 7.4 is perfect for Corydoras. Your selection of fish is a bit random though, and likely to cause problems in the long term. I personally don't like keeping Corydoras in tanks with gravel; they are much happier in tanks with sand. But clean gravel shouldn't cause Corydoras to die. Do check the water quality once or twice more today. Ammonia and nitrite can "spike" after feeding, while dropping down to zero a few hours later. Also check the other fish for signs of problems. If they're all healthy, I'd be tempted to just sit back for a month and not add anything new to the aquarium. Leave things be. Only afterwards, once you're happy the sick Corydoras was "just one of those things" consider adding more fish. Cheers, Neale>
Re: my poor catfish!! 8/22/07
Hi again, I think the poor little thing has finally given up the ghost and has passed away, I have read these are social fish so should I go and get another partner in case the one left gets lonely!! Any other advice would be greatly received. Thanks again for all you help so far Sharon <Corydoras do indeed need to be kept in groups, but I personally wouldn't add anything else to your tank for another month. Let things stabilise, and get a sense of how the tank is working out (or not, as the case may be). Ultimately, keep at least four Corydoras, preferably six. Ideally all one species, but they do often mix quite well, so you could get three of one kind and three of another. Cheers, Neale>
Re: my poor catfish!! 8/23/07
Hi Neale, thanks so much for all your advice, to be honest we just went for the fish we thought nice to look at, obviously we checked if they were suitable to be in the same aquarium as each other. If you've got time could you possibly tell me where we might be going wrong with the choice of fish. We have got fine gravel in our tank, would it make the bottom feeders happier if we bought a bag of sand and put that over the top or should we replace the gravel completely? As I said we are fairly new to this and are going on advice from shops and other people really. Oh by the way the Corydoras that I have left and the clown loaches still forage in the gravel is this normal if not how could I possibly stop them from doing so? Thanks again Sharon <Hello Sharon. I just went over your stock-list... mollies, tetras, a Betta, Plecos, silver shark, clown loaches and guppies. Right? OK, here's the low-down. Mollies and guppies need hard, alkaline water. Mollies 9 times out of 10 do better when the water also has a little marine salt mix added too. Tetras, on the other hand, almost always prefer soft and acid water. So right out the box you have fishes that need mutually exclusive water conditions. Bettas aren't great community fish because of their long fins -- they can't swim well, and end up starving or being nipped. Plecs (plural!) are large (typically at least 30 cm long, often 45 cm) and territorial fish. When kept in confined spaces they can and do fight, to the point where the aggressor will literally scrape the skin from the weaker fish. Yes, they're skinned alive... nasty or what? Oddly, they form schools in the wild. But for whatever reason this doesn't happen in the average aquarium. Silver sharks are also big fish (30 cm or so). They aren't especially predatory, but they're not stupid either, and if a small tetra or guppy swims in front of a 30 cm silver shark, that tetra or guppy stands a good chance of becoming dinner. Clown loaches are sociable and big (30 cm). They're also extremely sensitive to medications used to treat things like Whitespot. What do I mean by "sensitive"? If you're unlucky, they die. This isn't to say that your aquarium is doomed to disaster, but these are some of the issues you're going to have to work around as time goes on. Now, as for the gravel. It's fine. If you have plants, the gravel needs to be about 10 cm deep. If you don't have plants, keep only enough gravel to cover the glass. Either way, clean the gravel regularly by siphoning across it with the hose pipe. Some folks like to use those "gravel vacuum cleaners" but I don't use them. I prefer to siphon the sand, stirring the top level with a stick if need be. Up to you. Sand is preferable, in my opinion, to gravel in tanks with loaches and catfish because these fish simply enjoy digging into it. But sand is definitely an "advanced" substrate because there are some possible problems to using it, so for now, feel free to stick with plain gravel. I hope this helps. Cheers, Neale>

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