Cory Catfish with stubborn fin rot. Hi All, <Hello Lisa.> I am at my wit's end. Please help! This will be long, I'll start from the beginning. <Fire away.> I had 5 Sterbai in a 20 gallon long, moderately planted tank (Anubias and java fern) with soft, fine play sand substrate. It's got a nice piece of Mopani driftwood they like to sniffle on. It has 2 large sponge filters and an air stone. No CO2. I later added a small water pump and they like to swim in the flow sometimes. I got them in April 2019, online, shipped from a reputable seller. Right out of the box they were healthy and eating and sniffling around. They lived alone, just the 5 of them. I did water changes of 50% once a week, with sand vac. They get Fluval Bug Bites, Omega One Shrimp Pellets, and maybe once a week a mix of frozen bloodworms, daphnia, and brine shrimp. <All sounds fine.> Around mid-late May, I noticed 2 or 3 of them were missing little bits of their fins. No fuzz or white stuff, no blackening of the ends of the fins, no redness or irritation, just missing bits. I "medicated" with Melafix for about 5 days. No change. I medicated with 2 days worth of Kanaplex. I waited a few days for improvement, there was very little to none. I noticed one fish had it worse off than the rest, I spot-treated him with Methylene Blue a few times, no improvement (but! no staining on his tail?! So he's got intact slime coat), and within a few days it had gotten worse. Meanwhile, for about 8-10 days I did 50% water changes every other day. Still slowly worsening. Mind you, every fish is eating and swimming and playing in the bubbles, perfectly normal behavior. I remove the one fish, I'll call him Stubby. His tail was slowly but surely disappearing, and it looked like a little "chip" was taken out of his dorsal fin. I put him in a 10 gallon hospital tank on 06/26/19. This tank has a very thin layer of play sand and I put in a few mesh tunnels and some almond leaves for him to hide in. A day later I caught another fish (Chuck) that had dorsal and tail fin damage as well, not as bad, but it was there. <The wounds look clean and uninfected, which seems to rule out Finrot. Indeed, the holes in the fins look a lot more like what you see on wild catfish that have been victims of attacks by fin-biting predators.> I proceeded to medicate with Methylene Blue in the tank for 5 days, following the instructions on the bottle. No improvement in Stubby, Chuck might be getting better, hard to tell. They are very shy and run when the camera comes by. <Not unusual, especially if the Corydoras group is rather small. We usually recommend 6 or more, and in the wild, groups may number in the hundreds. It's hard to replicate that in home aquaria, but certainly the more specimens, the happier they'll be.> From then on, I have been changing water every day, still 50%. Stubby seems to have gotten a tiny bit worse, while Chuck is almost healed. They have now been in the hospital tank for 16 days. <Understood.> Hospital tank parameters: 77 degrees F., PH 8, ammonia 0, nitrite 0, nitrates 0. I do have 1 sponge filter and one box filter in there, both cycled. I keep the tank covered on 3 sides with a brown towel to keep them calm. No lights except when I do water change (desk lamp). I still do 50% water changes every day with sand vac. I make tea from Indian almond leaves, alder cones, and rooibos tea and add it every change. The water is a medium tea color. The fish, although understandably very shy, eat, sniffle around, and swim (when I'm not looking). <Water chemistry sounds a bit on the alkaline side, though it's hard to imagine a pH of 8 causing the symptoms seen here. Similarly, while Corydoras sterbai is a bit of a hothouse flower, with 28 C/82 F usually recommended, 25 C/77 F is the bottom end of their range, and should be tolerated reasonably well. So while I'd suggest kicking up the heater a notch, I can't see why lack of heat would be causing what you're seeing here.> I checked the 20 long where the other 3 Sterbai are, and yet ANOTHER fish has a little bit missing from his tail! <It certainly sounds like physical damage. Are there no tankmates with these fish? An over powerful filter might have the same effect, but you mention a sponge filter, didn't you?> I give up! I don't know what to do for Stubby, or any of them, really. I have asked in other places where to go from here, but I've only been told "water changes, water changes!" Obviously, it's not doing the trick! Kanaplex didn't work, MB didn't work...where do I go from here? What medication can I use next? <Assuming the fish are active, feeding, and growing, I would not continually medicate, certainly not until it becomes clearer what the problem is. If the wounds are clean, with no signs of Finrot (e.g., pink/white areas around the wounds) or fungus, I'd actually not medicate at all. In the wild fish routinely deal with bites and damage to their fins, and it's not a life-threatening situation at all. I'd perhaps move the whole group to a bare-bottomed tank (just in case the sand is sharper than you think) so that they can convalesce together in a dark, shady hospital tank with ideal water conditions. Some flowerpots or similar for shelter would be fine. I'd provide a bit of extra warmth, too.> I don't want to bomb them with too many meds but this has been going on too long without improvement for me to just leave it. Chuck seems much better, but I hate to take out Stubby's companion. I know they don't like to be alone. Should I just put them back in the 20 long and medicate that whole tank like I did in the beginning? What med should I use now? I'm at a loss, please help. <In honesty, I can't see any obvious reason for what you're seeing here beyond fin-biting. It's interesting that only the tail fins are damaged, while the whiskers look fine, and it's the whiskers that tend to go first if the substrate is 'bad' in some way. All very curious.> Pictures are hard to get but I have included some of Stubby. Many thanks for any help and advice you can provide, Lisa PS: I have another 20 long with adult albino aeneus, albino fry, and trilineatus Cory catfish and there's no fin rot, same substrate, same water change schedule, and they spawn regularly. Temp 76-77F. <Hope this helps, Neale.>

Re: Cory Catfish with stubborn fin rot.     8/2/19 Hi Neale, A lot has happened since I received your answer, which is why you have not heard from me in so long. I very much appreciate your reply! <Most welcome.> I am afraid that "Stubby" is slightly worse. I have moved my albino aeneus (+ 5 fry) and trilineatus to a new 40 gallon (total 9 adults). I then moved the sterbai (and 3 harlequin rasboras, fry I found when rehoming the adults a few months ago) out of the hospital tank and into the old albino tank, where the former occupants prospered and spawned. Temp is 78-80F. I broke down the old sterbai tank. At one point I was planning to put all the catfish in the 40 (albino, trilineatus, and the sterbai) but because of temperature differences I guess I should keep them separate? The sterbai don't seem very active although they do eat fine, and I believe I have 2 ladies because they are getting chubby. They are not too lively though, and I feel they must be bored with only the 5 of them. I'm afraid to get more because I don't want this problem, whatever it is, to spread to any new fish. If I put the sterbai in the 40, would they benefit from having a bunch of buddies, despite the temperature difference? I keep the 40 gallon at 76F. During the summer though, it can get up to 78F. <Do add an airstone, and be sure the water level is low enough they can easily swim to the surface to gulp air; generally, Corydoras shouldn't be kept in depths greater than 30 cm/12 inches, and ideally less.> I am still keeping them partially covered but have stopped changing water every day thinking that maybe it's stressing them out more. <Possibly, but weekly water changes should be maintained.> I did 2 days of Furan-2, but had to stop treatment because one of the fish stopped eating and was hiding. I did water changes, ran carbon, and he's fine now. I guess the medication was too strong. <Possibly, but antibiotics shouldn't really affect fish in any harmful way.> I now change the water every 5 days, although they've only been in their new tank about 10 days. Plus, we had a 4 day power outage last week, so they ran on a single sponge and water changes every other day. I can't win with these fish! I have sent two new photos, the best I could get...Stubby is slightly worse. I think Chuck must be better because I can't figure out which one he is now. Their new tank has a Tidal 35 hob and 1 large sponge filter. The hob is pretty gentle, and the albinos and 3lines never had a problem with it. I have the 3 rasboras, but they love to peck at each other and never bother the catfish. They've been moved around a few times and have lived with the albinos before the sterbai and were never a problem, not even the 9 adults I used to have. I know the rasboras need buddies or rehoming. I think I'll probably try to find them a new home. It is very weird :/ I always make sure everybody has their barbels and that they're long and pointy. <Good.> There is no whisker damage on any of the sterbai. I can't think of anything else I can do except to put them in the 40 with more friends, or get more sterbai and put them in the 20. I thank you very much for your help and patience! I'm so in love with these catfish, I want them to have the best lives I can give them. I have included 2 new photos of Stubby. I apologize for the bad quality of the latest pic, I am keeping them with low lighting for now. -Lisa <Hard to tell the colours of the fish because of the low light, but do see the fin damage. I'm wondering about Red Blotch disease, a bacterial disease that can plague Corydoras, particularly newly imported (i.e., stressed) ones. Tetracycline or Minocycline are usually used to treat this, with varying degrees of success. Nonetheless, provided the fin damage on 'Stubby' is clear, without evidence of decomposing tissue (off-white) or congested blood vessels (orange or pink) then I'd not worry too much about his fins. Clean fin damage should heal, given time. Cheers, Neale.>

Hopefully final update on Blobby White Panda Corydoras     11/30/17
Hi Crew, back in October I wrote to you about some sick Corydoras I had in quarantine that had developed a white coating and we had a bit of to and fro on different treatments, whether to euthanise etc. Despite trying every treatment available to me I have slowly lost more and more of the Corydoras including one that didn't have any of the white patches, but whose mouth seemed to have become swollen shut by small warty or tumorous bumps.
Tonight I finally lost the last of the white bumped corys.
<Sorry to hear this.>
I still have 3 Panda Corydoras that are mostly clear, one has a white lesion on his tail which hasn't changed for weeks, the others look a bit odd around the nostrils or on their fins but seem fairly healthy.
<Understood. Would continue to keep these isolated for now.>
The 2 sterbai Corydoras that were in the same quarantine tank never showed any sign of this illness, and neither have the rasboras that are also quarantined in this tank.
<Odd, but I suppose a silver lining.>
To recap: samples I have tried to take of this white matter have resulted in scraping off a waxy substance with no details of note when viewed under the microscope.
<May simply be mucous and/or decomposing tissue, neither of which will show much under the light microscope at low powers.>
Affected fish look really terrible but have mostly had an active demeanour, eating and swimming fairly normally right up until the day they die.
With this last fish I caught him in his death throes (laying on his side and struggling to swim or orient) and decided to euthanise him since his condition was so poor and I did not expect him to get better. After netting him out he appeared to have a red lump, an abscess or tumor I guess, on his caudal peduncle which looked to have broken to the surface and might be what finally did him in.
<Agreed.>
Since, unlike the others, he had very thick bumps with strips of healthy skin in between, I became determined to try and get a good sample off him to have one last look under the microscope. Upon closer examination I saw two tiny blisters on his white bumps, which finally clued me in that these bumps are not ON the skin, they are IN the skin. Or, rather, maybe they are the skin, thickened?
<Could be either really, and without seeing the fish, impossible for me to say. The fact is that many skin infections do cause blisters just below the surface, e.g., Whitespot cysts. So in and of itself, the fact there's a thin layer of skin over a growth or cyst doesn't rule out external parasites or infections.>
The stickiness I experienced when trying to take previous samples would have just been slime coat. I tried to scrape the thickest white patch and it was much like when your hands are wet for too long and the thickest parts swell and become easily damaged.
<Understood.>
With this new information I Googled once more and almost immediately came across a page about Carp Pox (Cyprinid Herpesvirus)
https://www.koi-pond-guide.com/carp-pox.html and the picture on this site looks pretty close to the blobby lumps that
were covering my Corydoras. The description of waxy lesions and fish that remain active and with a good appetite also matched what I experienced with my fish. I don't know if corys are susceptible to this particular virus but it does seem they had something similar all along which would explain why none of the treatments I tried worked. The page lists Lymphocystis and epitheliocystis as other possibilities but none of the pictures I saw of those looked anything like what was on my corys (and I suspect the antibiotics would have treated one of those).
<Viral infections are very difficult to diagnose except perhaps in those cases, like Carp Pox, that the symptoms are well defined and familiar enough that aquarists can recognise them easily enough.>
Have you heard of Corydoras being affected by a fish herpesvirus before?
<No; it's generally regarded as quite species specific, affecting Koi, its Common Carp ancestor, Goldfish, and its closely relative the Crucian Carp.>
I do remember our government in Australia talking about releasing CHV-3 into our waterways to kill pest carp species which makes me think they are sure it doesn't cross to other species.
<Indeed; what experimental evidence I could find on this suggests that native catfish, eels, and Rainbowfish, among others, were all unaffected by the virus.>
Mistakes have been made before though - cane toads spring to mind. I can't find much more information out myself but I feel that I have finally got a satisfactory idea of what was going on. I have been pretty strict with not sharing equipment between this tank and my other tanks and now I'm wondering if the usual net-disinfectant etc and washing my hands, will be enough to prevent the spread of this virus. Any advice on this front would be appreciated!
<CSIRO feel that the virus is not going to risk Australian native fish, though that's primarily because there are no native cyprinids in Australia, so even if the virus adapted a little bit, there are simply no even halfway related carp-like fish in Australia it could mutate towards. Catfish are far too distantly related for this risk to be significant. It's a bit like how humans can get mutated versions of viruses that originally infect monkeys or apes, but generally don't get viruses that infect cats or horses.>
Anyway just thought I would pass on my findings and my suspicions that this case was some kind of viral skin infection. Perhaps in healthier or hardier fish it even may not have been fatal as it took 8 and 9 weeks to kill four
of my Corydoras. So for now I will continue to monitor this tank and keep everything isolated as before and I will continue with just clean water and good diet as the treatment.
<Indeed. Just because CHV isn't the issue here, doesn't mean a virus of some kind can't be in play. There absolutely are viruses that affect widely disparate species out there -- the DGIV virus that affects Dwarf Gouramis has also been detected in certain other species. How common this is, and how dangerous, is hard to say. One issue is that there really are so many viruses out there -- and as aquarists we can diagnose so few of them -- there almost certainly is a Corydoras virus out and about, we just don't recognise it.>
Thanks for your help!
Bronwen
<Welcome. I'd tend to put down your experiences to bad luck. Might be a virus, might not. Hard to know. I'd isolate the sickly ones for another couple weeks at least, but if the disease has otherwise 'run its course' it may have run out of species it can infect. The Rasboras can probably go into the display tank, and the Corydoras sterbai may as well, since they seem to be immune or at least not affected by the virus, bacteria or pathogen. Good luck! 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 Driftwood 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..... Thanks! PS - Going to attempt to get a couple of pics to send as well <Good> 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 Driftwood 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..... Thanks! 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: http://www.fishchannel.com/fish-health/disease-prevention/red-blotch-disease.aspx 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. <Yes> 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. <Good> 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 <BobF>

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.>

Sick Albino Corydoras       3/20/16 Hi crew, Firstly, thank you for the reply to my previous email about my snails. Today I am writing about one of my albino Corydoras. She has been so happy and healthy until yesterday. As a matter of fact she has been laying bunches of eggs in the recent weeks. Three of her fry are a few weeks old and going strong(I'm a first timer)! Before I go into her symptoms I just want to mention a change I made recently that raised ammonia for the first time in nearly a year. A week ago, I transferred about a dozen juvenile and 2 senior apple snails into her tank(29 gallon planted, sanded tank with 9 Corydoras, 4 zebra danios, 6 white/black skirt tetras, moderate number of trumpets and a few Nerites). I noticed red spots on her yesterday and today there were more. After testing the water the only thing out of the norm was ammonia which was 0.25 ppm. Aside from the red spots she is lethargic, generally inactive and appears to have swollen eyes (one more so than the other. I'm concerned that this is more serious than ammonia poisoning because she is the only fish showing any symptoms. I have isolated her to a floating container in the tank for now and attached some pictures. Thank you for taking the time out to read my message. Danielle <Hi Danielle. Your little Corydoras has a type of opportunistic bacterial infection that is sometimes called "Red Blotch Disease" by catfish keepers because of its appearance. The non-zero ammonia is almost certainly part of the story, but I'd also be checking if the substrate needs a good clean and making sure there's a good current of water passing over the substrate. Basically, it's a result of stress. Tetracycline is the usual medicine for Red Blotch Disease, but improving living conditions is absolutely crucial as well. Don't forget to remove carbon (if used) while medicating. The swelling can be reduced by adding Epsom Salt at a dose of 1 tablespoon Epsom salt per 5 US gallons/20 litres. Hope this helps, Neale.>

re: Sick Albino Corydoras       3/21/16 Thank you very much for your help Neal. <Welcome.> I had read through the site about this issue and re-read the threads and articles after receiving your response, so I would like to share the results with you. As mentioned in one of the articles on your site (http://www.wetwebmedia.com/ca/volume_6/volume_6_2/mycobactera.htm ) , I did see results simply based on changing the main cause which in this case was water quality. After running errands most of the day(including picking up the tetracycline), I returned and noticed a major improvement in my Cory. <Good; these are normally resilient fish.> The only thing I did was isolate her to a floating tub (daily water changes) and added the Epsom salt as you suggested. I've attached pictures of her which were taken immediately after adding the first dose of tetracycline. I chose to go ahead with the antibiotic just in case the changes I've made aren't enough for her to make a full recovery. <100% the right thing to do.> However, it's clear that the improved water quality and especially the addition of Epsom salt are responsible for her progress. <Could well be.> The swelling has gone down so much that I wouldn't even be able to recognize her if she wasn't separated from the others. Can't thank you enough for your help and patience. Danielle <Nice to hear a happy ending! Cheers, Neale.>

Cory with hole in the head? (Bob, anything to add re: Red Blotch Disease)<<Nothing further>> - 10/12/10
Dear WWM,
I have a Corydoras julii with a hole in the head! It started out looking like a small scrape just above the mouth, but in the past week has eaten away at the flesh until I can see part of the "nose" bone. I also just
noticed a similar spot behind the left pectoral fin. These spots are flesh colored, with nothing in or on them from what I can see. The fish is breathing rapidly with pink gills, but otherwise eating and swimming fine,
although has slowed down a bit. The other fish are not affected by this.
This fish is in a mature (cycled since March) 10-gallon aquarium with four neon tetras, one black neon tetra, and a Bristlenose Pleco. I have had the Cory for a few months now. The water conditions are as follows:
Temp: 78 degrees, although with cooler weather it goes down a few degrees at night.
<Good; ideal water temperatures for most Corydoras are between 22-24 C/72-75 F. Keeping them much warmer than this will shorten their lifespan.>
pH: 7.8
KH: 120-180
Chlorine: 0
GH: 150
Nitrite: 0
Nitrate: 5-10
Ammonia I have not checked in a few weeks, but assume it is zero.
I have been very sick the past couple of months and have not been able to clean the tank properly, although I have more than adequate filtration (Whisper Power 20 and Aqua Clean 20 powerhead with undergravel filter).
I combed this site looking for answers and I didn't see any (not to say that they aren't there, but that I may have missed them.) I did find some helpful information such as proper diet for Corys and that they are social fish, so kept by themselves they may be stressed. I will remedy these as soon as I am able, but my main questions are 1) what is this? and 2) can I treat it? I have had this problem with Corys in the past and have just euthanized them because they're only a couple bucks and I was using them for "maintenance fish", not very attached to them - although I do like them.
Thank you for any help you can give me! Vanessa
<Hello Vanessa. It's unlikely your fish has Hole-in-the-Head. For whatever reason, this isn't usually a problem with "primitive" fish such as catfish or carp. My guess would be you're dealing with a bacterial infection. Some are opportunistic. A common problem with Corydoras is to keep them in tanks with gravel. While gravel isn't in itself dangerous, it does trap dirt and in the process cultivates bacteria. Should the gravel also be abrasive, there's a double whammy there because the abrasions on the belly, fins and especially the whiskers become open wounds, and bacterial invade these and cause infection. Healthy Corydoras should have quite long whiskers: I've got some Peppered Corydoras in a tank with sand, and the bigger specimens around 5 cm/2 inches long have whiskers a good 1 cm/0.4 inches long, and distinctly tapered at the ends. Corydoras kept in tanks with gravel commonly have abraded whiskers that are much shorter, barely a few millimetres beyond the mouth, and the whiskers have blunt ends as well. If your Corydoras have whiskers like that it means the substrate is dirty and/or sharp, and either way, possibly both, your Corydoras are being subjected to low level bacterial infections. This isn't fatal, and many
Corydoras are kept this way and live for years. But it is a sign that conditions aren't 100% perfect so far as Corydoras are concerned. Cleaning gravel regularly helps a lot, and that usually means using a gravel vacuum.
Reverse-flow undergravel filtration will also help. But it should go without saying that smooth, lime-free sand is infinitely better for Corydoras than gravel, and no-one who keeps them in sandy tanks would dream of switching them back to gravel! Among other things, sand is kept clean by the catfish themselves, so bacterial infections are far less common. Now, the second possibility is the infamous Red Blotch Disease. This is a systemic bacterial infection that is usually caused by poor shipping but can come about through unhealthy aquarium conditions. A broad-spectrum antibiotic may help, together with, curiously enough, a teaspoon or two tonic salt per gallon, the salt in itself not being a cure but somehow reducing stress on the fish during the antibiotic therapy. Red Blotch Disease is less common today than it once was, aquarists largely understanding what it is Corydoras need to do well. But because you have had this problem before, my guess is that you are doing something wrong in the way you're keeping these fish, which is why you keep "failing" to keep Corydoras spp alive for long. Review the needs of these fish, and act accordingly. One last thing, should you need to destroy affected fish, be sure to review humane methods of doing so; some of the old school approaches, like laying fish on crushed ice, are now recognised to be neither fast nor painless.
http://www.wetwebmedia.com/euthanasia.htm
Cheers, Neale.>

Help with treatment plan for Platies/Corydoras 1/12/11
Hi.
<Salve!>
About a month ago Neale and Bob were able to provide me with some help regarding my 40 gallon freshwater tank that houses Platies and Corydoras and set me on a sane path after I panicked and made matters worse.
<Oh.>
Originally, I was having issues with my KH rapidly dropping. Attached below is a portion of that correspondence in case it helps with history; however I believe I have sorted that out with switching to RO water and using crushed coral. I have been able to raise the carbonate hardness slowly and currently it is holding at 4
<Degrees KH, presumably, and good for a wide range of tropical fish.>
and my pH at 7.6.
<Also suitable for a very wide range of tropical fish.>
I also was able to get my ammonia and nitrites to zero (they had been spiking).
<Likely as water chemistry stabilised, water quality improved as well, the bacteria being sensitive to water chemistry changes, particularly pH drops.>
If you remember, I had done massive water changes and subjected my fish who had been living in a chronic acidosis state to acute alkalosis then acute acidosis (rapidly dropping pH) and back again. On 12/14 I stopped the massive changes and began the smaller 15-20% daily changes with R/O water buffered to raise the pH slowly. All of my fish had developed fin rot and mouth fungus at this point. I medicated with Tetracycline for 4 days and although I initially lost all my Platy fry under about 1 month old and my remaining Peppered Corydoras, my adult platies, fry over about 1 month old and Albino Corydoras survived and they rot cleared up and they started to heal.
Fast forward to 3 days ago (also current readings):
40 gallon tank
Live plants (multiple all true aquatics)
DH 10
KH 4
pH 7.6
AM 0
Nitrite 0
Nitrate 10
<All sounds fine.>
My Albino Corydoras spawned for the first time in a year or so and the Platies were very active and then I started noticing a problem - one Platy was hiding in a corner. At closer look, she seemed to have some gill damage and damage on top of her head and I attributed this to maybe not being able to recover from previous ammonia damage and the infection that followed the acute shifts in water chemistry. She died yesterday and 2 more adult Platies started hiding in a corner and another is not hiding yet but is not as active. One of the ones hiding has very red gills but the other two have no visible (to me) signs such as damage, gasping, red gills or spots. I thought maybe I hadn't treated them long enough and they still had some type of bacterial infection so yesterday I started Maracyn treatment because it treats for similar infections as the Tetracycline but doesn't turn the water that red color (and is not photosensitive).
<I would agree with you that a stress-related bacterial infection such as Mycobacterium could be responsible. These will create sores and cause infected fish to become lethargic, to breathe heavily, to hide away, and eventually to die. Dead patches of skin commonly appear as white flakes, much like sunburned skin on humans.>
Upon further observation, one other Platy that is very active has white spots flaked on its body. I looked at pictures today and it appears to be Ich. When the original issues with water changes and the fin rot were going on, about 4 of my adult Platies had this similar appearance but it seemed to clear with the antibiotic and I attributed it to being fin rot (this is my first time dealing with either condition).
<Finrot is generally very distinctive, beginning with cloudy patches in the fin tissue and pinkish blobs on the fins, the cloudy patches being dying cells and the pinkish blobs blood vessels congested with bacteria. After a few days the fins erode from the edges inwards, making the fin look ragged, often with the bony rays persisting for longer, the end result being a bit like a cobweb.>
Now through reading, it seems that ICH is only visible for one week and it's possible that they were suffering from both infections and ICH. I'm just not sure. I haven't introduced any new live stock to this tank in well over a year, but as with the bacterial infections, I now somewhat understand ICH is latent in tanks and ready to attack the weak.
<Ich/Whitespot can certainly trigger bacterial infections because the open wounds caused by the bursting white spots as they mature allow "bad" bacteria to get into the fish. On the other hand, stress can allow Whitespot and bacterial infections to become established independently of one another. So figuring out which came first is hard. By the way, there's very little scientific evidence that Whitespot can lie "latent" in tanks because the free-living stages need to find a host within a day or two, at least at tropical temperatures. What *may* happen is that low level infections persist unnoticed for months, and only when something goes wrong do the fish show high enough numbers of cysts to be obvious. Either way, treating proactively will break the cycle. Since the salt/heat method is harmless to fish, shrimps, filter bacteria and plants, this is a no-brainer for me -- treat with salt/heat, if only to cross Whitespot off the list of possibilities.>
These fish have been through HELL over the last month and I'm not exactly sure what I'm dealing with as so much has happened and I'm scared to continue the Maracyn or treat for ICH especially with the Corydoras in the tank. Can you advise the best way forward?
<Mycobacterium infections are essentially incurable, but Finrot and Whitespot should both respond well to prompt treatment. Do read up on these three, and act accordingly.
http://www.wetwebmedia.com/ca/volume_6/volume_6_2/mycobactera.htm
http://www.wetwebmedia.com/fwsubwebindex/fwich.htm
http://www.wetwebmedia.com/fwsubwebindex/FWFinRot.htm
http://www.wetwebmedia.com/fwsubwebindex/SaltUseFWArtNeale.htm
>
Thank you,
Gina
<Cheers, Neale.>
Re: Help with treatment plan for Platies/Corydoras 1/15/11
Hi Neale. I hope your weekend is treating you well. Thank you for all your assistance.
<Glad to help.>
I've read through the articles and I agree that ruling out Ich is a good idea; however '¦
I increased the temperature to 84 degrees over a day and a half and added the brine mixture (2 teaspoons of aquarium salt per gallon mixed in warm water put in the filtration flow path). I know you state the salinity is trivial for Platies but after adding about half the mixture, my Platies began to show sensitivity (hiding at the bottom and top of the aquarium).
<I doubt the salinity is the issue here. Platies can, do live in brackish water much more salty than this.>
Since they've been subjected to fluctuations in pH and ammonia and nitrite, unstable conditions, recovering from fin rot, could they just be less able to handle any change at this point?
<Seems unlikely. It's important to remember the difference between correlation and causation. Just because one thing follows another, it doesn't mean the first thing caused the second thing. If the Platies were sick or stressed already, then they might have gotten worse whether you added salt or not. Just make sure you're adding the right amount of salt, and that you're doing it in the right way. I'd turn the heat down a bit -- Platies come from quite cool habitats, and I'd not warm them above 28 C/82 F.>
The dilemma I face is that although they don't seem to like the salt, the one Platy who was hiding originally, came out today to swim for the first time in days today which is encouraging. While the other Platy with white spots has lost several of the bigger spots but is more lethargic which is encouraging and not so encouraging. My ammonia and nitrites are rising yet again (it seems the good bacteria doesn't like the changes either). The last dose of Maracyn was last night so I can up the water changes to reduce these levels more. I'm hoping without the strain of medicine and better control of ammonia and nitrites levels, the Platies will handle the current salinity better. I just want to make sure that my decision to not reduce the salinity is a good idea considering the Platies are showing sensitivity to it. I feel like we're (the fish and I) are damned if I do and damned if I don't at this point. I don't know which is the lesser of two evils.
<Would use the salt/heat method regardless.>
All but two fish are showing interest in food, the original sick one and another that I believe is severely constipated. I know I shouldn't be feeding them per the ammonia and nitrite, but I was trying to get the constipated one to eat a pea.
Also, in my reading of Ich, I've learned it can transmit on anything wet but I couldn't find instructions on how to handle transferring new plants into a tank per this possibility?
<Treat plants as potential sources of Whitespot. Quarantine any plants taken from tanks with fish in it, or for that matter from tanks likely to be on the same water circulation system in the pet store. Plants bought online from aquarium plant growers should be safe though.>
Thanks,
Gina
<Cheers, Neale.>
Re: Help with treatment plan for Platies/Corydoras 1/15/11
Okay, great. I've turned the heater down to 82 F. I didn't think the plant quarantine all the way through. I was thinking that you would never be able to tell if the plant had Ich on it but if quarantined, there wouldn't be a fish host to continue the cycle.
Once again - thank you.
Gina
<Yes, if the free-living parasites are unable to find a host within a period of time, they die. At tropical temperatures, that's about 24-48 hours. At room temperature, it may be several days longer. But I'd isolate plants for 7 days, at least, to be fairly sure they weren't carrying Whitespot parasites.
Cheers, Neale.>

Re: Cory died, another acting stressed (RMF, Red Blotch Disease? Pimafix better than Melafix?)<<Both equally worthless IMO/E>> 10/18/11
Hi, I've been trying to determine the cause of my Cory cat's death by searching online and have not found anything that quite matches his case.
There were three corycats living in a 75 gallon tall community tropical tank with over filtration by 2.5x,
<What do you mean by this?>
temp. in high 70's,
<Do bear in mind Corydoras are happiest between 22-25 C/72-77 F.>
and naturally hard water.
<Not normally a problem for farmed Corydoras at least.>
The tank itself is very tall 3ft long, in order to suit angelfish.
<But do note the temperature preference above isn't ideal for Angels. An exception is Corydoras sterbai, a species that thrives at 28 C/82 F.>
This tank system has been running for 4 years now, but it has been transferred from a 55 to a 50, then the current 75 using the same filter or filter media. The substrate is a mix of round, small gravel, newly added
plant substrate, and there is a strip of black sand. There are several giant hairgrass plants and a couple rocks.
<Okay.>
The corycats have been with us for a year and I had never noticed a problem with them before earlier this week when one looked wider and larger than usual. I thought he had simply been growing but then I observed redness right inside his mouth. The redness then covered his face and it looked like bright red sores.
<Have seen this, and is described as "Red Blotch Disease" by some. The red sores in the gut and gills are characteristic, and could easily appear inside the mouth before spreading elsewhere.>
He started to dart up to the surface for air repeatedly.
<Typical stress reaction.>
In a day or so he had trouble relaxing at the bottom of the tank and instead swam a few inches above the substrate. The Cory was darker in color than usual. I did a major water change, treated the water and tried
to keep the temp. steady. I also moved the tank from a center part of the room to a corner to reduce possible stress. Then I added Pimafix for two days (after removing the carbon from the filter.)
<Not used this stuff, but is surely not much use when treating this systemic bacterial infection.>
Also added a large airstone and increased surface movement.
<Good.>
He lasted only a couple more days, getting worse and worse, losing swimming ability, floating face up, face down, upside down, and face up with mouth at the surface. It appeared that his gills were not functioning well enough and that he was dependent on the surface for oxygen. His swollen body looked awful and his was face very red with sores. I kept him in a net at the surface eventually to keep him from being caught in the filter and he died.
<Usual outcome. Initially at least, a combination of antibiotics and slightly brackish water (1-2 teaspoons salt/US gallon) has been reported to help. But serious cases are almost always fatal.>
Now, another Cory is starting to swim from side to side of the aquarium over and over. There is no sign of redness on this fish or bloating. I removed the 2 cories from the main tank and put them in a 30 gallon long
with only sand, but the distressed fish is still swimming in an up and down wave across the front of the glass. The third Cory is acting normally.
<I see.>
There are a few changes recently made that I am wondering about, whether they contributed to this instability in the tank:
- New plant substrate - it is small and shard-like, it used to be under the regular substrate but when I vacuumed the gravel more of it came to the surface. Could the Cory have lodged some in his mouth?
<Sharp substrates are always a danger with catfish. Whether or not they caused enough damage to the mouth to start his bacterial infection is hard to say. But yes, could easily be a factor. Instead of sharp sand, use smooth silica sand or fine gravel.>
- New water conditioner - couldn't find my usual brand so got Aqueon Water conditioner, used it to top off the level of the tank earlier in the week prior to symptoms.
<Unlikely a problem here.>
- Just started feeding freeze-dried bloodworms, might have overfed.
<Again, unlikely to have caused the problems described, though freeze-dried foods should be used sparingly in fish prone to constipation or bloating.>
- Introduced 5 new smaller tetras from pet store - 3 of the 2 died but they didn't seem very strong to begin with. The remaining two look healthy.
<Possible factor.>
- New plants introduced over time.
<Not likely a cause of problems.>
- One of the older tetras is looking very thin and has trailing white and thin poop and I found that this may be a parasite.
<Thin white faeces are more likely just that, thin, slimy, mucous-rich faeces. May or may not be associated with gut parasites.>
- Just noticed after performing the water change and moving the fish that several of the larger tetras now have some white cloud in the middle point of their eyes. Could this be injury from net capture and transfer?
<Yes and yes.>
On the other hand there could be a build up of chronic stress from something like the tank being in a high traffic area? The cories had lived with angelfish the longest, then more recently black-skirt tetras and smaller silver dollars; too many semi-aggressive friends?
<While a possible factor, Corydoras generally avoid trouble from midwater fish. If their fins aren't actually being nipped (some fin-nippers do go for Corydoras fins) then this isn't likely the immediate cause of problems.
Even if their fins are nipped, it's unlikely a bacterial infection this serious would occur so quickly.>
Thank you for your help, it's been so frustrating and I want to take care of these fish..
Rachllea
<Red Blotch Disease is associated primarily with Corydoras shortly after import and transport. It's a bacterial infection that may be latent in all Corydoras, but become serious in fish exposed to stress, poor environmental conditions, overstocking, and generally poor care. It's not widely seen these days because the handling of aquarium fish is actually pretty good, and if nothing else, faster air freighting has ensured a quicker source-to-retailer period of transit. In any case, if these Corydoras have been settled in for a year, and only just starting getting sick, the likelihood would be that something about your aquarium isn't right. I'd look at substrate conditions. Check water flow is vigorous at the bottom of the tank. The bottom level of the tank is often oxygen-poor because filters can easily end up churning only the top and middle layers of water. Look how far down the inlet to your filter goes. Put some flake at the bottom.
Does it quickly roll about, or just sit there? Is there a lot of organic matter accumulating among the plant stems? Combine an abrasive substrate with less the ideal oxygenation and you've got a scenario that could cause Corydoras to sicken quickly. Cheers, Neale.>
Re: Cory died, another acting stressed 10/18/11
I recently wrote an email asking about my corycats and realized after reading some of your Amazon Biotope responses that black sand, specifically Black Tahiti Moon sand is too hard on Cory fish.
<Indeed, and Carib Sea recommend against its usage in such aquaria.>
I neglected to mention that the black sand in the tank is a new feature and that it is that Tahiti Moon type. Also I need to add more detail about the filtration: the filter is a canister, Rena Xp3, which is also about a month old and using filter media from the previous hang on filters. I read on your site that canisters can hurt oxygen levels and they bring water up from the bottom.
<Mixing two things here. Yes, they remove oxygen from the water column, which you need to compensate for by allowing turbulence and good water circulation throughout the tank. Usually this isn't a problem unless the tank is far overstocked. As for bringing water up from the bottom, this is what you want: leaving a layer of water sitting at the bottom of the tank would be very bad! This filter is quite a good one, but do ensure it's regularly cleaned, and that the outflow ruffles the water surface enough to drive off CO2 and help O2 get absorbed.>
As my tank is very deep I thought this might be a clue to what is hurting the bottom feeding fish.
<How deep? Corydoras dislike tanks 45 cm/18 inches or more deep, and ideally should be kept in tanks that are shallow enough they can easily dart up to the surface. In deep tanks, opt for Brochis splendens, a similar but deep-water catfish.>
Hopefully it is ok for me to clarify these details in a reply.
<Cheers, Neale.>
Re: Cory died, another acting stressed 10/19/11
I appreciate your reply to my case about the Corydoras illness. Mentioned in my previous question was a black-skirted tetra with stringy, white feces that may or may not have a problem.
<Difficult to say if related. Do try the Epsom salt/cooked peas treatment to see if related to constipation. But yes, farmed fish often carry diseases, and once in the community tank, can infect other fish.>
I've been keeping a watch on him and have noticed he's not eating and has gotten very thin.
<Not good.>
This morning he has PopEye. There is a small white fuzzy spot on one of his fins. Been doing some searching and was wondering if I should medicate with Metronidazole for a bacterial/parasite problem?
<If this was me, and this fish is exhibiting a wide range of symptoms and steadily getting worse, I'd euthanise to remove it from the overall analysis of your aquarium. Clove Oil is good for this.
http://www.wetwebmedia.com/euthanasia.htm
>
Is it likely everyone else is affected?
<Very difficult to be sure. Many parasites are host-specific, while others can infect a variety of species. A good approach is to assume that all are infected, and treat the tank. But you also need to identify what the actual problem might be. Metro is primarily used to treat protozoan parasites that live in the digestive tract of fish, such as Hexamita. While Metro has some antibiotic properties, it isn't the ideal antibiotic for treating, for example, Finrot and other external bacterial infections (including, most likely, those that cause Corydoras Red Blotch Disease). So you may decide to use two antibiotics together. This shouldn't cause any problems to the fish, but may affect the filter bacteria: keep a nitrite test kit handy, and if necessary, be ready to replace "dead" filter media with healthy media taken from another tank (or removed from this one before medicating and kept "alive" in shallow water).>
Thank you for helping us with our questions,
Rachel
<Glad to help. Cheers, Neale.>

Albino Cory and fin rot -- 10/18/07 Hi Bob-- <Well, it's Neale right now; hope that'll do.> I hope you are doing great. As always, let me please start with thanking you for the WWM web site and opportunity to share my concerns / problems / questions with other aquarists. <Cheers!> I do have a question about and a problem with fin rot in Albino Cory. <Ah, Finrot... almost always an issue with water quality. If it ever gets caused by other stuff, that's news to me. So, always review water quality while treating Finrot.> Few months ago my little Albino got that disease. In the aftermath of that fin rot my Albino lost its dorsal and pectoral fins... ;--( I acknowledge I was afraid to medicate the fish assuming that changing water will be much more beneficial than dropping medication... Perhaps, I was wrong. <Indeed you were wrong. It's a 2-step process. Water changes are essential to maintaining good water quality. No question. 50% weekly is my recommendation. BUT, while using a medication, you can't do water changes. Water changes would (obviously) dilute the medication, reducing its efficacy. This is also why you remove carbon from the filter (if you're using it, and you shouldn't be in my opinion). Carbon removes medication, reducing its efficacy as well. Regardless, it's not an "either/or" situation -- you do water changes to prevent problems, and use medications (stopping water changes) when problems arise. When the medication course is finished, resume water changes.> On a regular basis, every Wednesday and Saturday, I change 30% of my 25-gallon tank water... The pH range reads between 6.8 and 7.0. The water temperature is ca. 76 F. The ammonia level is 0. <All sounds reasonable. I personally find Nitrite more informative than Ammonia though; ammonia can come from inorganic sources (e.g., tap water) and its absence tells you nothing about the Nitrifying bacteria that turn Nitrite into Nitrate.> I keep lots of plants (Cabomba & banana) and make sure the water circulation is quite fast (I have one Emperor filter + one small Hagen filter for 10-gallon tank and 2 oxygen stones). <10 gallons a little on the small side for Corydoras paleatus (which is likely what you have).> I am not sure what I am doing wrong, but there must be something I do not get right... I noticed that my Albino started loosing its caudal fins (I observed the fin became quite ragged and 1/2 "eaten"). <How often do you clean the substrate? It's often said that dirty substrates can promote secondary infections on benthic fish. No idea if this is true or not, but stirring the gravel every few weeks before doing a water change can't do any harm, so long as you don't uproot the plants.> At this point I have to acknowledge that I am clueless ;--( and desperately looking for help, before the entire caudal disappears. <I see.> Do you think that I should place Albino in a hospital tank and treat it for the fin rot? <No, Corys like to be in groups, and keeping them alone will stress the fish in question. Besides, you may as well treat the tank.> If so, what is the best medication (least harmful) I could offer to that little fish. <Corys are fairly tolerant of medications compared with more sensitive catfish. So any combination Finrot/Fungus medication will work here. Ideally, get something safe with sensitive fish and/or invertebrates, but it really doesn't matter too much. I happen to find eSHa 2000 very good with sensitive fish, but as far as I know it's only sold here in Europe. Mardel Maracyn is one alternative you might consider.> Sorry to "bother" you with my question... I hope you will be able to guide me toward the right answer. Thanks much in advance for your feedback. Anna <Hope this helps, Neale>
Re: Albino Cory and fin rot -- 10/18/07 Thanks much, Neale. I will try the medication on my display tank... Though, I am bit worried about my plants ;--( and beneficial bacterias if I do the process in the main tank. <Used properly, modern medications won't harm filter or plants. Just read the instructions carefully, and follow them to the letter.> I forgot to mention that I do clean gravel 2 x a week -- along with water changes (first gravel, than water). I noticed that my pH changes with - or + 0.2 value. That looks like a lot. <Hmm... that's not a dangerous change in itself, but it's the rate of change that matters more. Is this across one week, or six weeks, or what? If on a weekly basis, I'd be slightly concerned, but if over six weeks or more, I wouldn't be too bothered. All aquaria become acidic over time. Water changes reverse the pH drop, and increasing carbonate hardness (KH) slows the pH drop down. For a standard aquarium, a hardness of 5-10 degrees KH should keep the water chemistry stable between water changes. 50% water changes weekly should reverse any pH drops before they become serious.> Maybe I feed the fish too much ;--( <Always a possibility. Review the articles on feeding fish here at WWM or in your aquarium book. As a rule, one or two pinches of food per day are fine, and each pinch should be so small that all the food is eaten in 2 minutes. Catfish should be given their own portion of food, preferably at night. For a small school of Corydoras, a small pinch of sinking pellets or a single Pleco algae wafer per night will be fine.> Perhaps, this may be a reason why my Albino got sick ;--( <Overfeeding compromises water quality; poor water quality causes fish to get sick.> Anyway, I will try Maracyn. Hopefully it will help. <Yes I hope so too; good luck!> Again, thanks much for your help. I greatly appreciate your insights. Greetings from NYC, Anna <Cheers, Neale>
Re: Albino Cory and fin rot 10/20/07 Thanks much, Neale. I got the answer -- I feed my fish too much ;--( The pH changes occur within a week! The cycle becomes apparent -- too much food increases acidity. Water changes drop that factor, which increases again over the course of a week due too increased amount of food in the gravel. I am going to read more about proper feeding. Thanks much for your help. ;--) ANNA <Ah, yes, overfeeding can cause acidification. But also check other factors. Bogwood is a notorious acidifier of aquaria, especially if it hasn't been "cured" properly before use. Anyway, do try halving the amount of food you use, and see how that changes the pH. You might consider adding a chemical buffer to the system to prevent pH changes. Small amounts of crushed coral or crushed oyster shell places in the filter will do the trick nicely. As these dissolve, they raise the carbonate hardness (measured in degrees KH). For a standard community aquarium, you want a KH around 5-10 degrees. In a small aquarium, half a cup of crushed coral should do the trick, perhaps even less. You don't need masses, since you're not after a hard water aquarium like you'd use for a Tanganyikan cichlid tank. But a little extra carbonate hardness, just enough to inhibit rapid pH changes, would be a cheap and effective "insurance policy". Cheers, Neale.>
Re: Albino Cory and fin rot 10/21/07 Neale -- T H A N K Y O U so very much!!! ANNA -- I will follow your instruction. <Cool. Good luck, and enjoy your fish. Cheers, Neale>

Cory cat question, hlth. mostly 7/27/09
Hello,
<Hello,>
First here the specifics of my tank:
nitrates/nitrites= 0
pH= 7.2-7.4
Temp- about 70-75 degrees F
<While this low-end range is idea for most (though not quite all) Corydoras catfish, it is a bit low for most other tropical fish, so do be careful what you add. Platies, Otocinclus and Cherry Shrimps should thrive in cool, well-oxygenated water, but Bettas, not so much.>
Light- fluorescent for 12 hours a day total (timer is set for 2 hours on then a half hour off during the day so the bulb and ac/dc converter don't over-heat)
Plants- 6 small, broad leafed plants and driftwood
Size- 12 gallons
<Bit on the small side for adult Corydoras and Platies.>
Inhabitants: 1 male Betta, 3 female platy's, 1 small otty, 3 spotted Cory cats, a couple of cherry shrimp (I just noticed some babies too), more snails then I would like (and are constantly removing!)
<Keep your tank clean. Snails convert waste, particularly uneaten food and dying plants, into baby snails. The cleaner the tank, the less the snails can breed. Adding something like Clea helena (the Assassin or Snail-eating Snail) also works wonders. They're widely sold in England, and perhaps elsewhere.>
water change: 25% every 7-10 days, I treat the water with a water conditioner before adding it and match the temperature.
Background:
All fish have been together for about 2 months and get along very well (no biting or chasing, no one has damaged fins, all are active and eat well)
Problem:
I had a 4th Cory who about a month ago (1 month after I got it) became sick. I first noticed it would stay by itself, it lost weight, and its tail fin was slightly clamped and a little red at the base. I treated the tank with an anti-fungus agent containing Nitrofurazone, Furazolidone, and potassium dichromate as per the directions.
<Why did you treat for Fungus? Were there symptoms of fungal infection?
Just to recap: Fungus looks like tufts of short white threads. It's often compared to cotton wool. If you don't see this symptom, then Fungus isn't likely, and use of anti-fungal medications is a waste. Do always remember medicines are poisons! Overuse, or careless use, will cause harm.>
There was no change in the fish and he/she became increasingly lethargic and started having labored breathing (the tail was still clamped and the redness was spreading from the base towards the tip of the fin). I retreated the tank after 4 days and a water change (as per the product's directions) and there was still no change in the fish and all the other fish showed no symptoms. Finally, after about a week the fish died. The tail had white fuzz on it, it was very red and there was some marked degeneration when I found him in the morning.
<Now, white fuzz, which can be Fungus, will often appear when a fish has died, or is close to death. Fungus is part of the natural, healthy ecosystem in your tank. Among other things, it breaks down fish faeces into the chemicals the biological filter can process. But the flip side is that a moribund or dead fish is every bit as delicious to fungi as a lump of fish faecal material. The fungi just eat whatever they can find. In your case, this Corydoras may well have been sick because of something else, and the fungus was just an opportunist that jumped onto the fish as it was dying.>
I figured this was just a weak fish but then 3-4 days ago (its been about a month since the above fish died) another Cory has the same symptoms and all my other fish look completely healthy (I haven't added any new plants or fish in the interim). I tried the same fungus killer and it hasn't made a difference. The fish is getting worse and I doubt he'll be alive by tomorrow morning but I am worried that this will keep happening to my other fish and I do not know how to treat the water.
<First of all, what is the water quality? Corydoras must have clean water, so 0 ammonia and 0 nitrite are critical. Secondly, the water must have too-extreme a set of chemistry parameters. Aim for pH of 6 to 8, 5-20 degrees dH. It doesn't matter precisely what the values are, just that they are stable from week to week. Corydoras are otherwise very hardy, but in tanks with poor filtration they frequently become the first fish to get sick. This is because the bottom of the tank is the bit with the least oxygen and the worst water quality.>
I did a massive water change after the first fish died.
<Don't change more than 25% in any one day, unless you are 100% sure the new water has similar temperature, pH, and hardness.>
I was thinking of treating the whole tank with an Ick-clear product to cover my bases if its a more resistant fungus
<No, no, no... medication doesn't work this way. All you're doing is randomly adding one medicine after another. Instead, identify the disease.
Check water chemistry, water quality, and water temperature to factor out environmental issues (which cause some 90% of the fish diseases aquarists encounter). Then, if you are sure the disease requires medication, select the right medication for the job, and use precisely as instructed. Do not use more than one medication at a time, and always remove carbon (if you use it) while medicating. Don't do water changes while the course of medication is being used (this applies to those that require several doses across several days). When you're done, do two or three 25% water changes across the next couple of days to flush out any remaining medication *before* adding any new medications (or additional courses of the medication used first time around).>
Other than that I do not have any ideas, please help!
<Cheers, Neale.>
As a side note, is there any safe product to combat snails that will not kill my shrimp Also, I don't plan on replacing the 2 fish that died because I think the tank was slightly over crowded even though the water was within healthy parameters.
<See above. Never, ever add anti-snail medications to an aquarium. They do far more harm than good. Cheers, Neale.>

911 sick Cory with fungus!!! 10/23/06 <Hi, Pufferpunk here> I have an established (1 year and 3 mo.s old) 10 gallon tank with two neon tetras and three albino Corys, which I have had for about a year. I use the smallest size natural gravel that one can purchase from the store. I use no aeration but that from the filter, an Aquaclear 20 gallon. I change my activated carbon every other week, and do 20% water changes every week. Ammonia 0, nitrites 0 and nitrates usually 0 (see explanation below). I have had some difficulty establishing a neutral or slightly acidic pH due to the fact that about nine months ago I bought what I found out later is a hornwort plant. pH kept rising and couldn't figure out why--finally found out that hornwort raises pH and despite all my attempts to buffer the pH, finally had to get rid of hornwort. I tried using Publix drinking water (pH 6.5), then Publix purified water (pH 7.5) but have returned to my original formula, which is to do 15 - 20% water changes per week with distilled water, then add some Flourish to add back some of the minerals, and also, a small amount of Flourish Excel for CO2 for the plants. Here are my questions. First, one of the Corys has been stripped bare almost of all his fins and tails in the past six months, and I am wondering if it is the pH instability I have had. He still has his barbels and seems to have no rot at all. The other possibility is that I fed them two much live bloodworm (they love it so much) and I had a nitrate spike which I didn't find out about for a week, which may have eaten away his fins and tails. I now have Nitrizyme granules in the filter to prevent a future spike. <I wouldn't waste $$$ on a quick fix nitrate remover. The best way to remove nitrates is to do larger water changes, while cleaning gravel (You'll have to work around the plants). I do 50-75% weekly water changes on my FW tanks (depending on how they are stocked). The worst thing you can do to your fish is to cause the pH to swing up & down. Regular weekly water changes with tap water should keep the pH steady.> The other URGENT question is about a Cory I have had that started sprouting what looked like a white cotton ball from the side of his gills about a week ago. I started treating with Maroxy and Maracide II and quarantined him in a gallon and a half tank with an aeration stone. After four days the puff had turned grey/black but nothing else, so on the advice of a second pet store I added three quarters of a teaspoon of salt. Fish started being in obvious distress, but pieces of the fungus did start to fall off but not completely. The tank started clouding up which bloom I know is the beginning of the bacterial cycle, so I began doing 50% water changes, with water from the original tank and adding a little more Maroxy, etc., to compensate. Today I started a new treatment cycle and when I put the Maroxy, Maracide II and salt in the quarantine tank the little fellow started to fall over on his side. So, in a panic, I put him in the community tank, albeit the risk of a mass fishicide. He hasn't eaten in five days and is somewhat thin and weak. I DID start putting two teaspoons of salt in the big tank during water changes - I read on your site that for Corys the reduced ratio of salt is better than the usually 1 tbs per 5 gallons - so hope that will protect the other fish, but need to start treating him again. Should I start the Maroxy and Maracide II again in the quarantine tank? They really didn't seem to help that much. Another option suggested from the lady at the first pet store - she had 20 freshwater tanks at one time in her home, so her advice is better than the usual crap you get from pet stores - is to give the Cory a saline bath. She calls it her "when all else fails" method and has used is successfully with her fish. You raise the salinity to ocean conditions, watch the fish carefully, and the very moment it flops over, return it to normal conditions. Considering that the salt did seem to break off chunks of the fungus, I am thinking this may work. But what if it doesn't? <An uncycled QT must have at least 50% daily water changes on it, to prevent the fish from poisoning itself with it's own waste. You can treat the entire main tank with Melafix & Pimafix, without harming the other inhabitants or the biological filtration. If the fish is already weak/stressed, I would not put it in a SW bath.> And what's the most compassionate way to end his life if nothing works? I am not crazy about the putting them in the freezer method. <I would overdose with clove oil (found in the toothpaste/ache isle of a drug store) & then freeze. About 5 drops to a cup.> Your advice would be much appreciated - he doesn't have much time left from the looks of him and his suffering is hard to watch. I am also wondering whether to replace the gravel with sand to prevent future injuries, which is what I read causes the source of the infection in the first place. But the other two Corys do fine with the gravel. <I have used small-sized gravel with my Corys for many years. I hope he makes in. ~PP> Thank you in advance, Lisa

911 sick Cory with fungus!!! 10/23/06 <Hi, Pufferpunk here> I have an established (1 year and 3 mo.s old) 10 gallon tank with two neon tetras and three albino Corys, which I have had for about a year. I use the smallest size natural gravel that one can purchase from the store. I use no aeration but that from the filter, an Aquaclear 20 gallon. I change my activated carbon every other week, and do 20% water changes every week. Ammonia 0, nitrites 0 and nitrates usually 0 (see explanation below). I have had some difficulty establishing a neutral or slightly acidic pH due to the fact that about nine months ago I bought what I found out later is a hornwort plant. pH kept rising and couldn't figure out why--finally found out that hornwort raises pH and despite all my attempts to buffer the pH, finally had to get rid of hornwort. I tried using Publix drinking water (pH 6.5), then Publix purified water (pH 7.5) but have returned to my original formula, which is to do 15 - 20% water changes per week with distilled water, then add some Flourish to add back some of the minerals, and also, a small amount of Flourish Excel for CO2 for the plants. Here are my questions. First, one of the Corys has been stripped bare almost of all his fins and tails in the past six months, and I am wondering if it is the pH instability I have had. He still has his barbels and seems to have no rot at all. The other possibility is that I fed them two much live bloodworm (they love it so much) and I had a nitrate spike which I didn't find out about for a week, which may have eaten away his fins and tails. I now have Nitrizyme granules in the filter to prevent a future spike. <I wouldn't waste $$$ on a quick fix nitrate remover. The best way to remove nitrates is to do larger water changes, while cleaning gravel (You'll have to work around the plants). I do 50-75% weekly water changes on my FW tanks (depending on how they are stocked). The worst thing you can do to your fish is to cause the pH to swing up & down. Regular weekly water changes with tap water should keep the pH steady.> The other URGENT question is about a Cory I have had that started sprouting what looked like a white cotton ball from the side of his gills about a week ago. I started treating with Maroxy and Maracide II and quarantined him in a gallon and a half tank with an aeration stone. After four days the puff had turned grey/black but nothing else, so on the advice of a second pet store I added three quarters of a teaspoon of salt. Fish started being in obvious distress, but pieces of the fungus did start to fall off but not completely. The tank started clouding up which bloom I know is the beginning of the bacterial cycle, so I began doing 50% water changes, with water from the original tank and adding a little more Maroxy, etc., to compensate. Today I started a new treatment cycle and when I put the Maroxy, Maracide II and salt in the quarantine tank the little fellow started to fall over on his side. So, in a panic, I put him in the community tank, albeit the risk of a mass fishicide. He hasn't eaten in five days and is somewhat thin and weak. I DID start putting two teaspoons of salt in the big tank during water changes - I read on your site that for Corys the reduced ratio of salt is better than the usually 1 tbs per 5 gallons - so hope that will protect the other fish, but need to start treating him again. Should I start the Maroxy and Maracide II again in the quarantine tank? They really didn't seem to help that much. Another option suggested from the lady at the first pet store - she had 20 freshwater tanks at one time in her home, so her advice is better than the usual crap you get from pet stores - is to give the Cory a saline bath. She calls it her "when all else fails" method and has used is successfully with her fish. You raise the salinity to ocean conditions, watch the fish carefully, and the very moment it flops over, return it to normal conditions. Considering that the salt did seem to break off chunks of the fungus, I am thinking this may work. But what if it doesn't? <An uncycled QT must have at least 50% daily water changes on it, to prevent the fish from poisoning itself with it's own waste. You can treat the entire main tank with Melafix & Pimafix, without harming the other inhabitants or the biological filtration. If the fish is already weak/stressed, I would not put it in a SW bath.> And what's the most compassionate way to end his life if nothing works? I am not crazy about the putting them in the freezer method. <I would overdose with clove oil (found in the toothpaste/ache isle of a drug store) & then freeze. About 5 drops to a cup.> Your advice would be much appreciated - he doesn't have much time left from the looks of him and his suffering is hard to watch. I am also wondering whether to replace the gravel with sand to prevent future injuries, which is what I read causes the source of the infection in the first place. But the other two Corys do fine with the gravel. <I have used small-sized gravel with my Corys for many years. I hope he makes in. ~PP> Thank you in advance, Lisa