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FAQs on Corydoras Cats: Systems

Related Articles: Callichthyid Catfishes, Summer loving: cats in the garden, kittens in the kitchen by Neale Monks,

FAQs on: Corydoras Catfish 1,
FAQs on: Corydoras Catfish Identification, Corydoras Catfish Behavior, Corydoras Catfish Compatibility, Corydoras Catfish Stocking/Selection, Corydoras Catfish Feeding, Corydoras Catfish Health, 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", fine, rounded sand... vs. larger, sharper-angled gravel.

Some species are cooler water, others more tropical...

Some can tolerate some salt, most really don't like it.


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.>

Corys and Lighting    12/1/14
Hello Crew, hope all is going well for you. I have a couple of questions, please. First, please tell me if Cory cats count against the total number of inches per gallon of water allowed without overstocking.
<Yes, they do. Most Corydoras are around 1.5 to 2 inches in length. You need at least 5 specimens, so that's something like 8-10 gallons for a small group of them.>
Also, I am setting up a (36” x 15” x 13”) innovative marine 30 gallon tank and would like to know how many lumens of LED lighting I would need. I will have freshwater fish with no live plants. I would like something that will bring out the colors of the fish and illuminate the whole tank without being too bright.
<Technically, you don't need any lighting for just fish! If you want to highlight the colours, then "warm" tubes (typically, around the 6500 Kelvin mark) work better than the "blue" tubes (upwards of 10,000 K) that stimulate optimal plant growth but do create such brightness fish often look washed out. Going the other way, the old GroLux tubes (around 5000 K) are amazing for making red fish look even redder, but plant growth is indifferent under them, and algae sometimes becomes a problem if you don't have any rapid plant growth at all. So I'd suggest sticking with warm, sunlight-replicating tubes, rather than blue or GroLux tubes, and while you're not after plants as such, adding some floating Indian Fern or something else to control algae may be necessary.>
Thank you for your time. James Hall
<Most welcome, Neale.>
Re: Corys and Lighting; sys.      12/2/14

Thank you for the help. I have one more question please. I am considering what type of substrate to use and I have heard that aquasoil is very good.
<Indeed it is. As are various similar products from other manufacturers. All are better than gravel, though none magically make plant growing easy if lighting isn't right.>
I have used both sand and gravel before; but with sand I tend to vacuum up some of it when trying to clean.
<Indeed. Best to avoid vacuuming sand if possible; allow fish or snails to sift the sand, and gently siphon off mulm where it collects.>
Is aquasoil OK for freshwater aquarium with fish only?
<If you don't plan on growing (sensitive) plants, then Aquasoil is a waste of money. It's safe, but a very expensive substrate, and the additional nutrients it contains may well spur some algal growth you don't want. Plain peat or coir fibre will do much the same in a fish-only system at a fraction of the cost, and coir especially is very cheap and ecologically sustainable (which peat extraction almost always isn't).>
Does it raise or lower pH, and does it get compacted where it can form dead spots?
<Most of these organic soils and substrates will lower the pH a bit. They're often made from peat plus various chemicals, though not always. Depends a lot on your carbonate hardness and/or use of Discus buffer. In soft water, yes, you can find the pH drops, but in medium hard to hard water, or soft water with Discus buffer, pH should be stable. Dead spots are sort of the point with these substrates. To clarify: plants can't extract mineral nutrients easily from soil with lots of oxygen. So plant-friendly substrates tend to create dysaerobic to anaerobic areas -- areas where the specific mineral ions that form are the "available" ones plants can use.>
Thank you very much. James Hall
<Most welcome. Neale.>
Re: Corys and Lighting      12/2/14

Thank you again Neale, Sorry for another question, but could you tell me a substrate you would recommend other than sand that tends to be easier to clean (if there is such a thing) and less likely to form gas pockets?
<Gas pockets in sand is a bit of a myth, so I wouldn't get hung up over it.
Think about it for a moment. Marine aquaria contain fish infinitely more sensitive to poisonous gases than freshwater fish. But what substrate do they use? Yep, sand. Ah, you say, but they have worms and snails and shrimps cleaning the sand. Yes they do, but so does the freshwater hobby, in the form of burrowing snails (Clea helena and Tylomelania snails or Lumbriculus worms if you don't fancy Melanoides spp.) and plant roots (which carry oxygen down into the substrate). Indeed, sand is beneficial in freshwater tanks precisely because anaerobic decay reduces nitrate levels, though this effect requires a 'deep sand bed' rather than an inch or so.
Put another way, if you have plants, their roots keep sand clean. If you don't have plants, then you only need a thin layer of sand to cover the glass, and that won't be deep enough for gas pockets. But if you're totally adamant you don't want sand, then peat (or better, coir) can be used in aquaria as a soft substrate. Hmm... would have you doing some reading:
Bob has an older article here, with much of value:
But I will opine that the fear of hydrogen sulphide has somewhat diminished in recent years, with (a) a better understanding of how quickly it oxidises and (b) a realisation nobody frets about the same thing happening in ponds despite all the mud in them! Still, if you have sand and you don't want gas building up there, and don't have plants/snails to prevent such from occurring, then stirring the sand as Bob says will inhibit, even prevent such problems. So, many options, but for most aquarists still come down to gravel, sand or peat. Oh, I use slate chippings in my tank with messy but non-burrowing fish (Panaque specifically, a very dirty fish). Slate chippings come in various colours: purple, green, grey etc; they make a nice dark substrate. Can be obtained from garden centres easily, at low
cost -- at least in the UK. Check pond safe before use though. If they are, should be safe in fish tanks too. Cheers, Neale.>
Re: Corys and Lighting      12/2/14
Thanks again. Is there a particular type of sand you would recommend,
<Smooth silica sand (lime-free sand) is widely used. Sold as such in aquarium shops and garden centres; in many places identical with pool filter sand that is much cheaper. Various "premium" aquarium sands are available but check these are safe with catfish and soft-bellied livestock (such as loaches) before use. One such is Tahitian Moon Sand from CaribSea, a beautiful dark sand for planted tanks, but too sharp for catfish.>
and are there any easy to keep shrimp I can put in a fish only freshwater tank?
<Cherry Shrimp and Amano Shrimp are very easy, but small enough to be damaged by larger fish. Work well with smaller fish (Ricefish, White Clouds and Celestial Danios for example) but wouldn't recommend for regular communities. Larger shrimps are available, but often difficult and/or dangerous. Bamboo Shrimp need filter-feeder food. Long-arm Shrimp are territorial and potentially predatory. Hmm... do see species lists at Petshrimp.com.>
<Welcome, Neale.>
Re: Corys and Lighting
Hello again, I wanted to ask if I use a small layer of sand (1-11/2 inches) and have no critters to stir up the sand is there still a good chance of having no gas pockets? Thank you again.
<Should be fine, but to be honest you don't even need that much sand. Just enough to cover the glass and shore up any rocks/wood. Less sand = less risk. Cheers, Neale.>


albino Cory barbell loss, going for air ‏            11/9/14
Hi there,
My name is Gabby and I'm new to aquariums (had one since August) and loving it. I've slowly built a community tank (doing lots of research) since then and it's gone quite well.
I have a question about my albino Cory. I have a group of four and yesterday saw that the smallest one had lost his barbels. Today, I've seen him go up for air quite a bit, much more than the others. He's still quite
active, but during feeding seems to have eaten less than the others. Should I just keep monitoring him? Any suggestions?
<Catfish lose their barbels for two reasons. Or rather, there are two things going on that interact, resulting in the barbels getting shorter.
Keeping Corydoras catfish in tanks with gravel (especially sharp gravel) rather than sand causes the barbels to get damaged. Very fine (sometimes called "pea") gravel is better than regular aquarium gravel, but the best
substrate is silica sand (a lime-free sand, sometimes called "pool filter" or "smooth silver" sand). What happens is the barbels get damaged, and that's when the second part of the process, bacterial infection, sets in.
The bacteria cause the tissue of the barbel to die back, and over time the barbels get shorter and shorter. Improving filtration and water flow along the bottom level of the tank can help. Some filters (especially small
internal canisters and hang-on-the-back designs) often don't "suck" much water from the bottom and the outflow is very much directed along the top of the tank. This means the lower half of the tank suffers from low oxygen
levels, which causes catfish and loaches to swim up and gulp air. Note that under optimal conditions Corydoras rarely gulp air -- they're very much "facultative air-breathers" meaning they only breathe air when forced to do
so. That's unlike Bettas which are "obligate air-breathers" meaning they will suffocate if they can't breathe air because their gills are proportionally smaller than they should be (in the wild, Bettas live in places where the water doesn't hold much oxygen, so relying on their gills alone would be pointless). Anyway, under better conditions the barbels grow back very quickly, and on healthy Corydoras you'd be surprised how long they get, not far off half an inch!>
I also have a question about his lost barbells. When I decided on Corys, I decided on sand. The guy at the aquarium shop told me coral sand works, but now I'm wondering if it's the cause of his barbell loss.
<Coral Sand was a terrible choice. Bad advice from the retailer there!
Coral Sand is made of limestone. It's from the sea, basically mashed up seashells and corals. It makes the water hard and alkaline (i.e., raises the amount of minerals in the water as well as raising the pH). Over time, this stresses most freshwater fish. (Not all: livebearers and Rift Valley cichlids LOVE coral sand because it creates conditions they want. But Amazonian and Southeast Asian fish come from soft, acidic habitats and they aren't going to do well in tanks with lime-rich sands.>
The other three and their barbels are fine. Is this sand too rough?
<See above.>
Any thoughts or recommendations would be much appreciated. This little school is rivaling my Betta for favourite status, and I want to make sure they are healthy and happy.
<For sure a fun group of fish, the genus Corydoras.>
Thanks in advance,
<Most welcome, Neale.>
Re: albino Cory barbel loss, going for air 11/9/14

Hi Neale,
Thank you for your quick response! I'll go out and look for silica sand right away.
<Cool. Aquarium shops sell it, but it's often cheaper at garden centres.
Just clean it well, or you'll make the tank really cloudy.>
What would you suggest to increase oxygen flow at the bottom of the tank? I have a hang off filter.
<If all else fails, an airstone weighted down so it draws water up from the bottom of the tank (that's what the air bubbles do) to the top of the tank.
Cheap and cheerful. Alternatively, there are all sorts of small pumps called powerheads that do the same thing electrically. Finally, you could buy a small internal canister filter and place it somewhere at the bottom of the tank, maybe hidden behind some rocks or plants, and let it push the water around.>
Man, so much to learn still!
<Part of the fun of the hobby is the learning. Corydoras are easy fish, and very reliable for beginners, but there are one two issues with them. Would direct you to this page:
Various links at the top that will take you to interesting/relevant articles. Cheers, Neale.>Cory Cats; sys., beh.     11/2/14
Hello, hope all is going well there. I have a question about cories, please. I have 6 sterbai cories in a 38 gallon innovative marine aquarium which is 19 inches high. In the past in other tanks I have had cories swim to the top on occasion for gulps of air and then go back down to the substrate. But now it seems these cories seem to swim up and down a lot and across the tank a lot and I have never seen one go all the way to the surface. Is this because the tank is so high? The water quality is good and the cories seem to be healthy. Thanks,
<Yes, James, Corydoras can have trouble swimming all the way to the top.
Like most catfish, they lack big enough swim bladders for neutral buoyancy, and need to active paddle upwards or they sink. In the wild they mostly live in streams that barely cover their backs rather than the main rivers.
So water depths in the 20-30 cm/8-12 inch range are ideal for Corydoras, with up to 45 cm/18 inches generally acceptable provided (a) the water current isn't so strong that the catfish have trouble swimming upwards and (b) there aren't any boisterous or aggressive tankmates that might harass them as they swim to the top. Water temperature and water circulation are critical factors too. Corydoras are facultative air-breathers, meaning they only breathe air when they need to. Cool water has more oxygen than warm water, which is one reason Corydoras mostly do best between 22-25 C/72-77 F, and only one or two traded species, notably Corydoras sterbai, being truly happy up to 28 C/82 F. In cool water they may hardly ever gulp air.
Water circulation at the bottom of the tank is what ensures there's oxygen down there for them to use, but most filters operate by pushing water along the top of the tank. Water circulation at the bottom of aquaria can be pretty poor, so review your system, and act accordingly. Adding an airstone or a small powerhead could make all the difference. Again, if the bottom layer of water is well oxygenated, they may not need to gulp air. If your Corydoras seem otherwise happy, chances are they're fine, but you're right to be open minded. Although Corydoras are normally very hardy, some mysterious deaths of Corydoras could easily be down to suffocation in situations where they need to breathe air but for some reason aren't able to do so. Cheers, Neale.>
Re: Cory Cats    11/2/14

Thank you Neale
<Most welcome.>

10G Corydoras sterbai tank... Using WWM       6/20/14
Hi there,
First of all, big fan of the site. We have an established (4 years or so) 10 gallon tank occupied by just 3 Corydoras sterbai. I have a couple goals for our setup: (1) Encourage barbel regrowth for our oldest member (2) reinvigorate our flora so I could possibly start a shrimp tank and move the sterbai over to a new 20G long setup once we get some long term stability.
<Ok! And maybe add a few more specimens>

Goal 1:
I'm going to preface this by saying we've lost a few sterbai along the way - honestly probably 6 or so cories over the years. (This brings up a tangential question: have you ever lost a fish while performing a water change - presumably due to shock resulting from changing the water too quickly?)
<Oh yes; quite common... See WWM re my suggested S.O.P. for water changes... INCLUDING storing water ahead of time of use: HERE:
scroll down to the second tray>
This suggests we're doing something wrong but we are trying to be better fish owners which is why I am writing in today. In the beginning, the fish were actually mating and producing eggs & our plants were
flourishing but for some reason our tank health tapered off. As far as water conditions, let's see... water temp around 82F, we use water conditioner, and we are doing (irregular to be honest) 25% water changes every 2 weeks.
<Better to do every week... pre-mix, store the water...>
I'm going to get chastised for this but I'm not huge fan of these water tests so I can't provide nitrate numbers (they're a lot of work shaking and waiting and such.) Our hardiest sterbai has survived all 4 years but has lost her barbels. She is very active in the tank but even with weekly water changes haven't seen new barbels growing in. We tried a couple things starting with upgrading our filter to a Marineland Penguin BioWheel <https://www.petco.com/Shop/Product.aspx?SKU=989738> instead of the stock filter. Her newest companions (purchased 3 months ago) still have their long healthy barbels so the I'm assuming the water quality must be acceptable. What can we do to improve the quality of life for our fish?
<Need to know what you're starting with... dGH, KH... mostly...>

Goal 2:
We have a few java ferns and added some hornwort 9 months ago. The java ferns started out strong and were splitting left and right but growth has tapered off since. The hornwort has thinned out considerably since it was purchased. 2 months ago we replaced our hood light with a 15W Aquari Lux Light
<http://www.amazon.com/Aquari-Lux-Fluorescent-Lamp-20W/dp/B0002APWOC/ref=sr_1_31?s=pet-supplies&ie= UTF8&qid=1403242231&sr=1-31&keywords=penn+plax+light . >
<This isn't much photo strength. See WWM re Ceratophyllum, plant lighting period>
at the suggestion of our LFS. We also occasionally dose with API Leaf Zone
<http://www.amazon.com/API-Leaf-Aquarium-Plant-16-Ounce/dp/B0002566TW/ ref=sr_1_1?s=pet-supplies&ie=UTF8&qid=1403242387&sr=1-1&keywords=api+leaf+zone>.
I've since increased our timed light to 6 hours a day and decreased feeding (Tetra tropical flakes) to once every couple days to reduce fish waste (thoughts on this?)
<... Let's have you read here re Corydoras fdg:

at the suggestion of our LFS. Do you have any suggestions on what we can do to encourage more plant growth in our tank?
<All sorts... and all archived on WWM... Learn to use the search tool (on every page), indices... Bob Fenner>
Thank you in advance,

Re: Water Chemistry and safety of fish (Cory sand/sys.) 8/15/11
Hi Neale,
Thanks. Of course, I have a couple more questions. We discussed how Marble Veil Angel's fins are never perfect, due to their immune system and the normal bacteria found in their tank water. Well, I have to accept this, even though I find it horrible. However, even so, is there anything I can use in the water to help the fins? I do a 30% water change every week, sometimes I notice the small roundish spots of fungus that eat the fin, then disappear. There is only a very small amount of fin gone, and looking at pictures of marbles, my fish seems to be doing better then most.
Last question, I have always used in my first tank, Aqua Terra Natural Sand over plant substrate. I have Cory cats in this tank, and have had them in there for at least four years, with no problems. With better
maintenance, no more lost barbels, as you suggested. I recently read that this sand is 100% acrylic coated, but has no dyes and chemicals. Is this coating bad for the Corys, in the long term? I also recently bought Estes Marine White Sand, which is supposed to be safe for freshwater and not raise PH, is this sand safe for Corys? I have now used one five pound bag of the Estes Marine and the rest was the Aqua Terra Natural, which is only an inch thick, over plant substrate, in my new 125 gallon tank. Both sands
seem to be fine and soft. It's the acrylic coating on the Aqua Terra that really concerns me. Oh I can't wait for my 125 gallon to cycle, it is taking a long time. Patience is a Virtue! Thanks so much Neale, and have a
pleasant day. Sincerely, Lu
<Hello Lu. I haven't used either Estes Marine White Sand or Aqua Terra Natural Sand personally, but if they are chemically inert they shouldn't harm the water chemistry. As for the Corydoras, well, the main thing is whether a sand feels velvet smooth or scratchy like sandpaper. If it's smooth, then it should be fine. Grab a hand lens and take a look at some. Are the grains like mini gravel chips and nice and rounded? Or do you see glassy, sharp edges like little flints? Acrylic coatings should be harmless; after all, aquaria can be made from acrylic, as are numerous aquarium ornaments and accessories. So provided the Aqua Terra Natural Sand is sold as fish tank-safe, then you're good to go! By the way, a really big tank like a 125-gallon one should be safe to use within 3-4 weeks, and quite possibly sooner, in the sense of being big enough to dilute any ammonia from a handful of small fish. I'd have no qualms about adding 3-4 Corydoras paleatus for example to a 125-gallon tank right from Day 1, and I'd use them to cycle the tank, though keeping a close eye on ammonia and doing daily water changes and minimal feeding. I also tend to add plants to new tanks as well: they remove ammonia directly, and also carry the bacteria that "seed" the biological filter, jump starting the whole process. Cheers, Neale.>
Re: Water Chemistry and safety of fish 8/15/11

Hi Neale,
Oh, great news. I called the company on the Aqua Terra was informed that the acrylic is good for life, and won't come off or harm the fish.
I researched more on the Estes and, as told by the person whom sold it to me, it is inert, and from reading, a lot of people prefer to use it, as it does not raise PH and is very nice and fine. I also am gonna get some Caribsea sunset sand, I love the color and read on WetWeb, that it is safe for soft belly fish.
<Good to know.>
I have had tank running for about three weeks now, using ammonia to cycle.
My ammonia level is at 0, but my Nitrites are still at about .50.
<Ammonia cycling can take a while. If ammonia is zero, but nitrite at 0.5 mg/l, chances are things are well advanced and should be done within a week or two.>
I am so glad I can put plants in now, cause of course, I am like a little kid, and cant wait to put them in.
<Is actually an excellent approach: gives the plants time to establish themselves without fish uprooting them.>
As a paranoid mommy, I am afraid to harm the fish, but I trust your knowledge, and will probably put those little Corys in! I will send you a picture of both tanks when I get them situated.
<Sure thing!>
You and WetWeb deserve a lot of credit for keeping me in the fish hobby, so I would love to share my tank photos with you!!!
<Why not start a thread over at the WWM forum? http://wetwebmediaforum.com/
Some folks like to create "journals" for new tanks, adding updates over the weeks so people can comment on them and provide ideas.>
Thank goodness for WetWeb and you!!! Have a splendid day. Cheers Lu
<Most welcome, Neale.>
P.S I checked out planted tanks on You Tube, and if your interested in seeing some breathtaking set ups here is the link:
If you put in search area and hit search it takes you right to it....enjoy!!!!
<Some real nice tanks there. Cheers, Neale.>


Tahitian Moon sand, laterite, and Corydoras 2/18/10
"Right now I have regular aquarium gravel in my tank. Is there any special type of gravel/sand I should use to prevent the Corys from getting injured and that is also good for the plants? Is laterite a good option?
<Corys seem to relish a sandy substrate, and so they're so much fun to watch as they sift through the sand! Also, it seems that Corys kept in tanks with gravel can suffer from broken barbels. I have about fifteen Corys in my community aquarium with "play" sand, and have had no problems with my Corys, so that's another option -- just be sure the sand you use is smooth silica sand, as I'm not sure how many different sands are called "play" sand. I think CaribSea is doing a lot in the way of freshwater sand substrates now, and they offer a variety of natural-looking colors, as well, so that may be something to look into (I have considered changing my plain old vanilla sand to their Tahitian Moon -- the black sand really brings out fishes' beautiful colors). I am not familiar with laterite, but
from what I've read (you've got me doing my research!) it seems the Corys should be fine with it. I didn't read anything that stated it was sharp, which is the only thing I'd look out for. (Bob, is this a correct summation?)
<<Yes... is physically soft-enough, not chemically harmful. RMF>>
This sounds like a great set-up, and one I think you'll really enjoy. The Corys are such characters, and you may even find yourself able to add a few more Neons after the aquarium is established and you've gotten a good feel for how heavily-stocked (Nitrate-wise) the tank is.>
<You're welcome!>
<--Melinda> "
Hello Melinda,
Before recommending people swap one type of sand for another, it's a good idea to have them look over the Carib Sea web site. It rates sands depending on two key things, whether they're safe with soft bellied fish (like catfish) or burrowing fish (like gobies). Tahitian Moon Sand for example gets a "no" on both counts. The problem is that sands made from the glass production industry (like Tahitian Moon Sand) is too abrasive, and scratches the mouths, whiskers and bellies of fish like catfish.
I'm not sure about laterite. The real stuff is mud rather than sand. I've only used real laterite as a supplement to pea gravel underneath a layer of smooth silica sand, the two separated by a gravel tidy. I can't really see why anyone would want a substrate made entirely from laterite mud; it's so darn expensive, and makes a real mess! But the laterite-enriched "complete" substrates are something else, and I don't know if they're made using glass or not.
Cheers, Neale
Am accruing on WWM. B
Re: Tahitian Moon sand, laterite, and Corydoras
Hi Neale--
Thanks for the information. I have read that folks have had success in using Tahitian Moon with soft-bellied fish, including rays, so is why I mentioned that I was considering changing my own substrate to the Tahitian Moon. Now, I'll reconsider, and it's good to know that even CaribSea doesn't recommend its use in tanks with those type of fish. I was not aware of the page you linked me to, and will look it over prior to suggesting sand or re-aquascaping my own tank!
As for the laterite, everything I found on WWM in my research to respond to the query did indicate it would be safe, but I did see in the process of reading that most folks don't use it as their sole substrate. However, I figured this individual may not be planning that, either, but wanted to know whether the laterite itself would be harmful. It's good to know that it's not, especially considering that this isn't a product I'm familiar with.
However, as I indicated with the "play" sand, it can be difficult to go on the name of a product in determining its safety -- for example, by laterite, was the querier referring to plain laterite, or these mixes you're referring to? I honestly don't know. I assumed plain, because nothing else was indicated, and based my response on that. Overall, I think as long as the querier takes care to avoid sharp substrate and moves toward soft, smooth sand, he or she should be okay, and I indicated that this was the reasoning behind my approval of the laterite.
Thanks again for taking the time to respond to my query-within-a-query! I had helped this person thus far, and wanted to continue helping, but since I was in unfamiliar territory with the laterite, with nothing to go on but what I found on WWM, definitely wanted to be sure I was providing accurate information.
Re: Tahitian Moon sand, laterite, and Corydoras
I don't know either, Melinda.
This might be one of those times where you recommend "consulting with the manufacturer" rather than risking your own reputation. For what it's worth, you're probably right, but I've never used a laterite-enriched synthetic substrate, so can't speak with any authority at all.
Cheers, Neale

algae eater/ bottom feeder with Glofish 02/14/10
Dear WetWebMedia Crew,
<Hi! Melinda with you here tonight.>
I have a 20 gallon aquarium with pebbles at the bottom and many artificial and 3 real plants. The aquarium is cycling right now and I am following the technique you outlined of getting used substrate from the petstore and leaving it in for ~ 3 weeks while checking.
<Are you adding an Ammonia source, such as a pinch of fish food daily? If you don't, the cycle won't occur -- there will be nothing for the bacteria to eat, so it won't grow.>
I have a few questions:
1. What parameters should I check in order to know whether the cycling is complete?
<Ammonia, Nitrite, and Nitrate. When Ammonia has spiked and fallen to zero, and Nitrite has done the same, and you have readable Nitrate, then it's time to do a water change and add your fishies. Have you had the opportunity to read
here?: http://www.wetwebmedia.com/FWSubWebIndex/fwestcycling.htm>
2. I am thinking of stocking this tank with 8 neon tetras OR 8 Glofish. I gather from your article on stocking that these should be fine. However, I want to add an algae eater/ bottom feeder to help in keeping the aquarium
clean. Is it ok and sufficient to add two julii Corys to this system?
<If you add Corys, you should add at least five or six, since this is how they're more comfortable. You've got plenty of "room," stocking-wise, to do so, as well. The Juliis would be a nice addition -- they're such nice looking little fish! The temperature ranges for any of these three fish are compatible, though I'd still use a heater, set low, to control fluctuations. Set it at 75, and it may only come on every now and then, but will give you the peace-of-mind that temperature isn't going to dip below that point.>
Thank you for all your help.
<You're welcome. Please write back if you have any questions.>
Re: algae eater/ bottom feeder with GloFish 2/18/10

Thank you Melinda.
<You're welcome!>
We have decided to go with 8 Neon Tetras and 6 Corys.
<That sounds like a nice combination!>
Right now I have regular aquarium gravel in my tank. Is there any special type of gravel/sand I should use to prevent the Corys from getting injured and that is also good for the plants? Is laterite a good option?
<Corys seem to relish a sandy substrate, and so they're so much fun to watch as they sift through the sand! Also, it seems that Corys kept in tanks with gravel can suffer from broken barbels. I have about fifteen Corys in my community aquarium with "play" sand, and have had no problems with my Corys, so that's another option -- just be sure the sand you use is smooth silica sand, as I'm not sure how many different sands are called "play" sand. I think CaribSea is doing a lot in the way of freshwater sand substrates now, and they offer a variety of natural-looking colors, as well, so that may be something to look into (I have considered changing my plain old vanilla sand to their Tahitian Moon -- the black sand really brings out fishes' beautiful colors). I am not familiar with laterite, but
from what I've read (you've got me doing my research!) it seems the Corys should be fine with it. I didn't read anything that stated it was sharp, which is the only thing I'd look out for. (Bob, is this a correct summation?)
<<Yes... is physically soft-enough, not chemically harmful. RMF>>
This sounds like a great set-up, and one I think you'll really enjoy. The Corys are such characters, and you may even find yourself able to add a few more Neons after the aquarium is established and you've gotten a good feel for how heavily-stocked (Nitrate-wise) the tank is.>
<You're welcome!>

Corydoras paleatus, stkg. # in a ten gal. vol. 11/1/09
I have a 10 gallon tank with two peppered Corydoras in it - they were given to me by a friend who was breaking down her tank. I have heard they like to be kept in groups - how large of a group can I keep in a 10 gallon tank, and what types of live plants should I plant it with? I have pool filter sand as a substrate.
<A ten-gallon tank is on the small size for this species, so in the long term, you want to think seriously about something around the 20 gallon mark. Smaller tanks are difficult to keep clean, don't tend to be stable, and don't provide enough space for fish this size to swim about and exercise themselves. Since the price differential between 10 and 20 gallon tanks is trivial, there's no reason to buy these smaller tanks that I can think of. They take up about the same amount of space, surprisingly enough.
But in the meantime, I'd keep a group of 5 specimens. Try to get more females than males if possible (females are bigger, while males have taller, more elongated dorsal fins). I wouldn't worry too much about live plants since you have a sandy substrate. The best bet would be some floating plants, like Indian Fern, and maybe a branch or two of bogwood with some Java fern or Anubias attached. To grow plants that have roots, like Cryptocoryne species or Amazon Swords you need a reasonably deep substrate, at least 5 cm, and that'll waste too much volume inside this tank. Better to go for a shallow bed of sand, maybe 1 cm, and stick with plants that get their nutrients out of the water. Cheers, Neale.>

...lone Corydoras 10/29/09
Hi Forum
Receive a best greeting. Two months ago try to start in hobby cycling a 10 Gallon tanks as recommended.
<You do realise 10 gallon tanks can only hold a limited variety of fish?
See here:
After a month and good Physical-Chemicals values...
<What was the ammonia source here? A common mistake is to cycle an aquarium just by adding water and letting the filter run. Without ammonia, nothing happens. The easiest approach is to add pinches of flake every couple of days, just as if there were fish in the tank. The flake decays, produces ammonia, and the bacteria in the filter grow.>
I acquire in a local pet store 5 nice Bicolor Corydoras.
<Corydoras bicolor, an interesting, somewhat delicate species.>
Misfortunately after a week they begin to die.
<What are the water chemistry and water quality values? Almost certainly an environmental issue. Just to recap: you need 0 ammonia, 0 nitrite, water hardness around 5-20 degrees dH, and a pH between 6 and 8. Water temperature should not be too high, no more than 25 C.>
For now just one survives and this one looks good and healthy. My concern right now is...put other companion to my lone Cory. The problem is Bicolor Cory cats is not common in the area and I cant find other ones. Can I put other types of Corydoras with him for example schwartzi or even pandas?....any other recommendation?
<Yes, Corydoras species can be mixed, but they do not usually school together. Sometimes they do, but not usually. If you have never kept fish before, and want a hardy species, then the best bets are Corydoras paleatus and Corydoras aeneus.>
Thanks in advance!!
<Cheers, Neale.>

Small tank, Betta, Corydoras sys. 5/12/09
Hi, I wrote in a few days ago about a sick fish and Neale told me that my tank is simply too small (3 gallons- 1 molly, 2 platies, 1 albino Cory).
Since them I have found a home for them and have been doing research on what kind of fish I could put in such a small tank. My research has come up with a beta.
<Yes, you can -- just about -- squeeze a Betta (rhymes with "better", not "beater") into a 3 gallon tank. But I wouldn't recommend it; chances of success are far greater in a tank at least 5 gallons in size. I cannot
stress enough how difficult it is to maintain any fish in such a small volume of water.>
However, my concern is that these other fish which have been in my tank since January have been sickly or the water has been off and so there has been lots of Melafix in that tank (the antibiotic I have been using which apparently is just as good as antiseptic). I've had what may or may not be fin rot, something that may be parasites or dropsy right now (swollen belly, white stringy poo_, I'm not really sure and probably much more disease in the tank than I would like to know about.
<Finrot and Fungus are latent in all tanks, since the bacteria and fungi involved are harmless, even beneficial, when fish are healthy. It's only when the fish get weakened -- often because the environment is wrong --
that these bacteria and fungi become dangerous. Ergo, keep your fish happy, and Finrot and Fungus are never a problem!>
So my questions are: is this tank truly suitable for a beta?
<Marginal. I wouldn't bother.>
I went through a lot of trouble with these other fish, I want a fish that I can enjoy. It's 3 gallons, filter, BioWheel, heater, and lots of hiding spaces.
<Seriously, three gallons is a bucket. You would do so much better keeping a Betta in 5 gallons or more; for 3 gallons, I'd keep Cherry Shrimps or Crystal Red Shrimps. They're pretty, they're inexpensive, and they're fun to watch. Kept properly, Cherry Shrimps breed readily, and it's fun to watch them at all different sizes.>
Secondly, should I clean the tank before I put the beta in?
<Certainly give it a clean, but there's no need to sterilise it, and certainly no need to throw away live filter media.>
If so, with what? Throw the gravel out? Just throw out the water and rinse the gravel to get rid of the old poo that might be buried under there? And for how long should I let the tank cycle, if at all?
<If the aquarium has been empty for more than a few days, chances are the bacteria have died back to a very low level. Not zero, but low. So you will want to cycle for at least 2-3 weeks before adding another fish. Shrimps produce less ammonia, so if you add just a three Cherry Shrimps immediately, and three a week later, you should be fine.>
I know it seems like I can just look these answers up and I have but there has been a lot of conflicting information and some suggestion that I clean my tank with BLEACH! My BioWheel has NOTHING on it, looks just as new as it did when I got it back in January (4 months ago). Could it be from all the Melafix?
And is there ANY WAY I can keep my albino Cory? I really like him and would be saddest to see him go.
<Sure, in a bigger tank. Since these are schooling fish, make the Cory happy by keeping six in a tank 15-20 gallons or larger. Keeping a singleton is cruel.>
Thank you
<Cheers, Neale.>

Re: FW Sand, part. Callichthyid sys. 4/27/09
In your last response to me you said something about using sand as a substrate for my aquarium, because the Corys love it and stuff. But I've read numerous places that sand is a pain to clean and you have to kind of move it around frequently.
<Garbage. In fact, the issue with sand is that it doesn't HIDE dirt, and so people imagine it's dirtier. It's like when people say white clothes get dirty faster. No, they get dirty just as fast as any other clothes, you just see it more quickly. What happens with sand is that fish faeces and other remains don't sink into the gravel. On a bed of sand, they sit on the top of the sand. If you have a good filter, this means it gets sucked up,
but if it doesn't, it collects usually in one corner. To be honest, it's actually easier to keep a sandy aquarium clean because you can see the dirt and siphon it out easily. A turkey baster is a good tool for "spot
cleaning" if you don't have time to do a water change. No, you don't need to stir the sand all the time. Your Corydoras will take care of that!
Melanoides snails are also great additions, behaving like earthworms and keeping the sand spotlessly clean. Plants also play a role, and besides doing extremely well in sand, if there's some nutrient rich aquarium soil
underneath, their roots oxygenate the sand slightly as well. Do see here:
Instead of using sand, though, I read that quartz sand is a really good choice.
<Provided the sand is smooth (not sharp) and lime-free, use whatever sand you like. Silica (silver) sand is what I use because it's so cheap and easy to buy.>
I was wondering if you knew anything about it, like if it's too sharp for Corys and if live plants are able to be planted in it (with something like Fluorite or Eco Complete underneath, or something along those lines) Here is a site with some of the quartz sand that I like
<Looks far too sharp. And hideous. Bright white substrates will make your fish "turn down" their colours, so they'll all look washed out. Trust me on this: plain "smooth" silver sand from your garden centre is (extremely) cheap and effective, and once you have some plants growing above to create some shade, fish love the stuff. A 25 kilo bag (a bit over 50 lb) costs me about 3-4 UK pounds, around 5-6 US dollars. Using it seems a no-brainer to me. Just make sure you don't get "sharp" silver sand, the alternative stuff
sold in garden centres.>
Once again, thanks :)
<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.>

Substrate for Cory Cats - 8/19/08 Hello, all! <Hello! Merritt here today before the dreaded school days start again!> I would like to add some Cory cats to my 14 gallon tank that currently houses a female Betta. Why do some sources say minimum tank size for Corys is 10 gallons and others sources say 30 gallons? Is this more for water quality or the fish's activity? <Good question. The Corys that I have had over the years have been contained in tanks smaller than 15 gallons but the species I kept did not get any bigger than 4.5 cm. I know some that can get bigger than 7 cm thus, a larger tank would be beneficial for them. All aquarium fish need excellent water quality. I would not worry about the size of your tank, 14 gallons will be fine. Just focus on the size your Corys that you will eventually get. You could easily have the ones that get up to 5 cm in your tank. Also, Corys are not very active fish, mine are at their peak of activity during feeding when the scavenging is good.> Anyway, should I be able to get the Corys... I currently have a pebble substrate, about 1/4" in size. I was thinking about switching this to a sand substrate for the Cory cats, because I don't know if they will be able to search for food in the pebbles. Is sand a better choice than the pebbles? If so, what kind? I read the "Nice Bottoms" article and it sounded like silica sand would be good for the cats, but other articles and questions I have looked at say otherwise. Some info states Black Tahitian sand as being smooth, others as being sharp. So, I am utterly confused by what to do here. Not sure that I can use any other types of sands with these fish. Any suggestions? Also, if silica sand is appropriate, where can I find it? <The only substrate that I use with my Corys is pebble substrate. They can and do find food easily with their barbels in the pebbles. Sand is a great substrate for Corys, because the fish can bury and dig in the sand, nothing is happier than a Cory in sand. If you want to switch to a sand substrate I would us the silica sand mainly for personal preference. The black Tahitian sand is more expensive, from what I have seen, than the silica sand. And many chose the black because they want a darker substrate for their tanks. The silica sand will not make the water alkaline and Corys prefer their water to be slightly acidic. Silica sand is mainly used with reptiles, so you need to be looking in unfamiliar territory. Just rinse the sand thoroughly before putting it in your tank.> One last thing - the tank has cycled. Will changing the substrate completely ruin this? Or can I count on the bio-wheel and other surfaces in the tank to keep everything in check? <Mmm... Just to be safe, I would recycle the tank. It can't hurt.> Thanks for the help, again! Amy <You are welcome! Merritt A.>

FW Blk. sand, Callichthyid/Corydoras sys. 2/13/08 Hi Guys. Do you know of any black sand that is safe for Corys? I've heard mixed reviews about the Tahitian Moon Sand and I love these little guys too much to just put something in because it looked cool. I'm setting up a 225G so I don't want to make the wrong decision. I'm pretty new to this, though I'm already smitten. Great work. Best, John <I can't offer any specific brands of black sand. Tahitian Moon Sand is apparently made from glass, and that's presumably why it isn't recommended for catfish. In theory any smooth, non-calcareous sand should be suitable. I use silica sand with Corydoras and it works great. Over here in England such sand is quite widely sold, though expensive. I must confess to being cheap and using the plain yellow stuff from garden centres. Cheers, Neale.>
Re: black sand 2/14/08
Thanks Neale. <John,> Nice to know you're from England. I'm a defected Scouser living in Los Angeles. <Move all that distance to get some peace and quiet, and then the Beckhams follow you! No justice.> Thanks for the info. John. <Good luck, Neale.>

Black Sand....The search continues - Attention Neale 4/29/08 Hi Neale, <Amanda,> I do hope all is going well with both yourself and all your fish. <Pretty much; thanks for asking.> As you can probably tell from my subject heading I am still searching for black sand (previous correspondence is attached because I'm sure you don't remember every e-mail you've ever answered). It's never taken me so long before to set up an aquarium, stock it maybe, but never just set it up. I've collected a dusting of black sand from my LFS (they're great, very helpful). Apparently about 6 years ago black onyx (??) sand was all the rage here in Australia and they still had a couple cups left from setting up display tanks that they kindly gave to me. However, the supplier they got it from has gone out of business. So now I have the finest dusting of black sand over the bottom of my tank and the search continues. I am now certain that 'proper' black sand exists nowhere in Queensland. I have found several things that claim to be black sand but one thing I can guarantee....it is not sand for aquarium use. I have found a couple stores in Victoria that stock 'CaribSea Tahitian Moon Sand' (for an astronomical price) but all they show is a picture of the bag. <Never used this sand personally, but is said to be safe to use in freshwater tanks. However, CaribSea themselves do not recommend using it with burrowing fish, likely because the grains are rather sharp (it's really a type of glass by-product from some industrial process). http://www.caribsea.com/pages/products/super_nat.html So personally, I wouldn't use it with Corydoras.> I've called the stores and asked them about it but they've been less then helpful with describing it to me and I am loathe to spend $100 to buy the sand (9kg is the only size bag I've been able to find here) and have it shipped (for an additional $50) to me only to find out it's not what I'm chasing. I have no issues spending the money if it's what I want. So my question is: Have you ever seen this CaribSea Tahitian Moon Sand and if you have is it the type of sand that I've been searching for (specifically something my Corydoras will enjoy foraging in)? <I have to say Corydoras seem to be among the fish that *don't* change their colors, and my specimens absolutely love plain vanilla silica (silver) sand from the garden centre. The smooth grade of this stuff (as opposed to the "sharp" sand) is sold here for about Ã'£3 per 25 kg. It is very widely used by gardeners and should be cheap and easy to obtain.> Thank you for you're help. After all this I might have to send you a picture of the final setup. I am thinking a school of Pseudomugil mellis, or possibly P. gertrudae may look rather stunning with a school of one of the more heat tolerant Corydoras species. <Pseudomugil are indeed lovely fish. Only occasionally do they get to the UK, but I have seen Pseudomugil gertrudae here recently. As for heat-tolerant Corydoras, Corydoras sterbai is the species of choice. As you seem to realize, most Corydoras are happiest at relatively mild temperatures, typically around 21-24 C.> Cheers Amanda <Cheers, Neale.>

Re: Black Sand....The search continues - Attention Neale Hi Neale, <Amanda,> Thanks for the reply and the link. I'm not quite sure how I managed to not think of looking up CaribSea directly to find out more about it. <Indeed!> It's good to know that the sand colour won't make a difference to the colour of the Corydoras. That having been said I've been imagining some species of Pseudomugil which could potentially look stunning with a black substrate. That combined with the fact that I quite enjoy the antics of Corydoras and would love to see them happy in sand is keeping me on the black sand search (might have something to do with my slightly obsessive compulsive nature as well). I have not ruled out the possibility of importing it (I know probably seems a bit excessive to most people, but hey, got to keep the fish happy, plus my husband hasn't said no....yet.....) my brother lives in the DC area in the States and he could have better luck finding something then I am. <Hmm... I think importing sand will be insanely expensive. Quite possibly collecting some river sand and making sure it doesn't have much lime content might be easier. If you're already collecting your own fish, finding a nice substrate shouldn't be difficult. On the other hand, do remember that the colour of silica sand depends quite a lot on the arrangement of the tank. If you have a lot of plants that cover the surface (such as Vallisneria trailing up and across the surface) the sand looks a lot darker. When I use this sand in planted tanks, I find the colour becomes far less objectionable than you might assume, especially once there's a bit of algae covering the grains as well. I'd suggest trying that approach for now, and simply replace the sand as and when you find a dark sand you like.> Pseudomugil are indeed a lovely fish. I fell in love with them the first time I saw them. I have a small collection but would love to get a few of the less common specie. I have a breeding tank of P. gertrudae (which was why I was thinking I might put some in the new tank, see how they colour up). I also have schools of both P. signifer and P. tenellus in two other tanks. Collected those ones myself. I've been waiting for an opportunity to get some P. mellis (they can be a bit harder to come by) but the ones I really want are the P. cyanodorsalis. Unfortunately they've been a bit scarce in the supply lists of late. I've been toying with the idea of going up north to Darwin or out west to Broome on a collection trip haven't decided yet though if I'll keep them fresh or brackish. I've heard of people having success with both but want to talk to a few more people about it, see which way I'll have the most success. <Do try and read Bruce Hansen's chapter on Australian Fishes in my brackish book. He does discuss Pseudomugil alongside lots of other small species that would work well. Not all Pseudomugil need brackish water, as you appreciate, but species like Ps. signifer really do well in it. If you're into native Oz fishes, chances are you've come across Bruce's work already; he knows his stuff, and my conversations with him are always very rewarding. Do also consider getting in touch with ANGFA; they may well have information on native sources of sand and other decorative materials suitable for this sort of aquarium. http://www.angfa.org.au/intro.html To be honest, I'm pretty jealous of Australian fishkeepers: there are so many wonderful species. I just hope all those "accidental" releases of goldfish and the like don't cause too much damage in the long term. The Australian fish fauna is amazing: with a couple of exceptions (lungfish, Arowanas) its made up entirely of brackish/marine fishes that have secondarily adapted to life in completely freshwater environments. We only very rarely see these fish here in the UK, mostly rainbowfish and occasionally a few gobies, blue-eyes and glassfish.> Look at me go on about blue-eyes. Thank you for your help. Will continue on my search. Cheers! Amanda <Best wishes, Neale.>

Corydoras ID -11/18/07 Lord, I hate to bother you all again. But I've spent several days at planetcatfish.com trying to ID this little Corydoras catfish and can't seem to find what he/she is. I ordered Corydoras trilineatus and 2 of these came in the same batch. I'm putting them all in the 125 gal with the Severum (after 4 wks quarantine). I'd like to get a few more of this species because I noticed Corys seem to hang out with their own species pretty often and I want them to be comfortable. If you can ID him for me I'd certainly be grateful and so would the little Cory. Thank you all, you're the most wonderful group of volunteers I've ever encountered. Mitzi <Hello Mitzi. Your catfish could well be Corydoras trilineatus. As you perhaps realise, Corydoras trilineatus and Corydoras julii are routinely mixed up. In fact many catfish experts reckon that most of the fish sold as Corydoras julii are actually Corydoras trilineatus. The give-away is the head: Corydoras trilineatus has black worm-like markings on its head, whereas Corydoras julii has discrete, approximately circular spots. Because your fish doesn't seem to have those spots on its head, I don't think it is Corydoras julii. I agree with you that Corydoras are happiest in big groups. Six specimens seems to be the minimum to really get the most from them. Kept like that, they are less shy and more entertaining, as well as easier to breed. Thanks for the kind words, and hope this helps. Cheers, Neale.>

Corydoras ID/tank height -11/18/07 I have a PS to the email below I just sent. I just read a quote from Neale at wetwebmedia.com/FWSubWebIndex/callcatdisfaq2.htm saying "<Circulation of the water is important. But also how deep is the tank? Corydoras are obligate air breathers, and they will literally drown in an aquarium too deep for them. For the smaller species, around 30 cm is about right. Anything over 45 cm is dodgy, in my opinion.>" This had occurred to me before but now I'm extremely concerned. The 125 gal tank I planned to put 12 Corydoras into is 22" tall (or 60 cm). Is that going to be too tall for them?? If it is I'll just buy them a 40 gal long and put some Hatchet fish in with them. Just when I think I'm done worrying I find out I'm not :-( I'd love to hear your opinions. Mitzi <Hello Mitzi. In deep tanks, small Corydoras may struggle to reach the surface. In a plain aquarium, 45 cm may be taken as a safe depth of water for medium- to large-sized species like Corydoras panda and Corydoras aeneus. Smaller species, like Corydoras hastatus, shouldn't really be kept at more than 30 cm depth. In deeper tanks, it's generally recommended you go with Brochis rather than Corydoras spp; Brochis are altogether stronger swimmers and naturally come from relatively deep waters. Corydoras are very much shallow water fish that inhabit creeks and streams rather than rivers. My peppered Corydoras live in a tank where the water is about 40 cm deep, and they seem fine. What I have noticed is they often rest half-way on stiff plants such as Anubias. So, if your tank is unusually deep, you might incorporate such resting places so that their life isn't too difficult. Do note that I'm talking about the depth of water rather than the depth of the tank; by the time you allow for the depth of substrate and the air space at the top of the tank, your 60 cm aquarium will likely only contain around 50 cm of water depth. While still deeper than the optimum, with a few robust plants, bogwood roots, or rocky ledges, your catfish should be fine. Cheers, Neale.>

Cory Cat Addition 2/25/07 Hi, <Hello.> my name is Colleen McCarthy, <My name is Adam J. but my friends just call me Action.> and I have a male Betta in a 2.5 gal tank. <Neat.> I was wondering if you think adding a Cory catfish or two would be okay. <Mmm...not in this size tank.> thanks, <Of course.> colleen <Adam J.>
Re: Cory Cat Addition 2/25/07
well what is the minimum size tank for 2 or 3 together? <The ideal setting would be at least a 10 gallon standard tank with some fake or live plant coverage for hiding...5 at a minimum in my experience.> colleen <Adam J.>

Salinity Woes 11/27/06 I recently bought 1 Pleco (3 inch), 3 Cory Cats (1inch), an Iridescent Shark (2 inch), and a Colombian Shark (2 inch) for my 55 gal. aquarium. I know that the sharks will outgrow this tank. <Yep> My question deals with the salinity of the water, as I found out (after the fact) that the Colombian Shark will prefer a brackish/marine environment as it matures. How much salinity will my other fish tolerate? Thanks! Kevin R. <Not much/any for the Corys and Pleco. This mix is not viable for the long term.> <Chris>

Catfish Questions 8/12/06 Hello WWM Crew; Thanks so much for your great help with my marine reef questions in the past! In addition to my 350 gallon marine reef system I also have a couple of freshwater tanks which I have had for the last four years or so. Here's a freshwater question you never received before! I recently obtained seven little darling Corydoras adolphi which are now doing great in my QT tank. I have had them for about a week and in another three weeks or so I will be placing them in my 75 gallon "Amazon" tank. The Corys are currently kept in water with a PH of 6.4 - 6.6, which is approximately the same PH as in my main "Amazon" tank. My question is this: Where can I obtain some reliable information about these little guys. I have all the usual reference books, but not a single one even mentions this species. Google shows only a few entries, none of which are of any help to me. I realize there are about 140-150 different species of Corys, all of which are from various parts of South America and living in waters from a PH of about 5 to a PH of about 6.8-7.0. I would really like to take good care of these critters, but how do you suggest I do that without knowing anything about them? (Other, of course, than "all Corys are about the same" - which is definitely not the case!) I hope you can steer me in the right direction. Thank you very much. Tage Blytmann < For all your catfish needs check out planetcatfish.com. Just type in the species name under the search and read away.-Chuck>

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>

Salt tolerance of Cory Cats 5/28/06 Hello Crew! <<Hi, Jasmine. Tom here.>> I understand that the salt tolerance of catfish in general is very poor. <<It's true that Catfish don't have a tolerance for salt at levels that other fish can tolerate quite well.>> I have some Otos, Bronze Corys and Panda Corys. <<I love these guys, Jasmine. The Pandas tend to be a little less "robust" than other Corydoras varieties but they're sure cute. :)>> For future reference when the situation eventuates, how much aquarium salt would you recommend for these fish for a) prevention of nitrite poisoning and b) disease treatment. <<Regarding (a), don't let this situation "eventuate". In a cycled tank, with proper maintenance, it simply shouldn't occur. As to (b), this isn't, unfortunately, an option because of the dosages necessary to be effective. The "cure" would be as bad as the disease, in a manner of speaking. Even with all of the benefits to be derived from the addition of aquarium salt, in your case, I'm reluctant to advise this. Neither of the instances you cite would lead me to recommend its use given that there are alternatives should the occasion arise. I hope it never does, though. ;)>> Thanks for your help! Jasmine <<Happy to, Jasmine. Tom>>

Restocking, Learning - 08/25/2005 Hi WWM Crew, <Hi, Wayne! Sabrina with you today.> I've been emailing you a lot lately; sorry for the inconvenience because the problems I've had seemed petty. <No worries.> I thought Corys would be fine living with goldfish and mine have been doing pretty well. But I was just informed I shouldn't keep them together because of the different temperatures they live in? <Quite true.> Anyways, I'm set on just keeping them separate, maybe giving my biggest goldfish (about 2.5 inches) to a petstore, and restocking my tank with the peppered Corys with fish that are compatible. <Sounds like a plan!> I have 4 peppered Corys in a 10 gallon tank so far. I think 1 female and 3 males because one is significantly larger than the other 3. <Actually, a good ratio, if you wish to breed.> They've been chasing her around during these past few days. She (if it's a female) looks like she's trying to swim away from them. Seems like they want to mate with her. Is it stressful to her to be the only female in the tank? <Not really.... Provided, of course, that there is plenty of cover for her to hide.> I want to add maybe 2 more Corys to the school nonetheless. Would that be too much for my tank? <Pushing it, but they'll be fine. Corys are VERY social animals.> I've also read some stuff on freshwater livestock and compatibilities saying Tetras (Neons, Cardinals, Black Skirts, Bloodfins, False Rummynose, and Penguins), Platies, Loaches, and White Cloud Minnows? are good for a community tank. <I would skip white clouds, as they are actually a more temperate fish.... prefer cooler water.> I don't want any more bottom feeders or fish that like to hang out on the bottom. <Skip the loaches, then.> I'd prefer fish that stay in the middle of the tank or the top. Also after reading about size and water quantity, how big will tetras, platies, and loaches grow? <Much variance for tetras.... depending upon species, less than an inch to over a foot! Just research the species you like. Platies, roughly 2". Loaches, again, much variance.... from a couple inches to over a foot. Again, research....> Do they live in the same water conditions as my current Corys? <All but the platies, yes, but even the platies will thrive with you.> Are there any other types of fish I can think about putting in the tank other than the ones I listed? <Uhh.... how big is this tank going to be??> I also don't know how many of those fish I can add along with let's say 6 peppered Corys already in the tank. <As above.... I don't know the tank size (I do recall corresponding with you before, but we go through sooooo many emails daily.... Can't remember every detail! Mostly, be sure not to go overboard on stocking. It's always better to have too little than too much bioload.> I don't want to have an overstocking problem like I did with the goldfish. <Ahhhh, very good!> Thank you so much and you guys have been very helpful! <Glad to be of service.> I'm starting to understand more about fish care and also gaining much needed knowledge for future the well being of any future fish! <That, my friend, is why we are here. Thank you very much.> Wayne <Wishing you well, -Sabrina> Restocking, Learning - II - 08/26/2005 Hi Sabrina, <Hi, Wayne!> Thanks for replying! I have a 10 gallon tank. I think it has completed it's cycling phase, ammonia 0, nitrite 0, and nitrate looks like 20ppm maybe slightly more. <Best to get the nitrate down some with water changes - but otherwise, great.> I have a bubble wall and an action pirate ship bubbler. <No other cover? I'd recommend adding more stuff for the Corys (and future fish) to help them feel secure and be able to "get away" from one another. Plants (plastic or live, low-light plants), rock, even very clean, new terra cotta plant pots.> My filter is a hang on back Whisper 20 Power Filter and my tank temperature (and also room temp) is 78 - 82 degrees. When it starts to get colder I'll drop the heater in. <Perfect.> I have the 4 peppered Corys already in that tank and was just wondering how many fish (Corys, Neons probably, or platies unless there are other types that will thrive comfortable even after they are fully grown) <I'd go for platies, honestly. They are MUCH more entertaining - and durable - than Neons. Neons can be very, very delicate and sensitive to any changes in water quality. Platies are VERY forgiving, especially in regards to pH, hardness, and nitrate. Plus, they come in SO many great colors/patterns.> Are panda Corys more delicate than peppered Corys because <Not really.> I love the way they look. <Me, too.> If they are too delicate, I would probably skip buying them and just add 1 or 2 more peppered Corys. <Well, platies are schoolers and like to be in hoards of their own species (literally, can find them in schools of hundreds, maybe thousands, in the wild!), but they'll play well with other species, too. Pandas are my favorite, as well. You could mix these two.> I visited Petco today and if Neons would do well in my 10 gallon tank I saw some neat tetras that were an inch or less in length. The only probably is that they school and I'll have to get at least 5? (read somewhere odd numbers were best) for them to feel comfortable? <Mm, the odd number thing is bologna - it's just important to have them in a school of several. Again, I'd do platies instead of tetras, here; if you're totally bent on having Neons, yeah, no less than five.> I would like to add some color (blue, red, orange, etc) to my tank that are not bottom dwellers. <Yup, you want platies! Err, at least, they satisfy your color desires :) A trio of platies and your small group of Corys would do well in this tank, provided you keep water quality in check.> Lost interest in goldfish because of how messy they are. <Ahh, dig a pond! You'll get interested again right away. Goldfish are AWESOME, given the proper environment. Wishing you well, -Sabrina> Restocking - III? IV? - 08/30/2005 Hi WWM Crew, <Hi, Wayne! Ya got me again!> Sabrina answered my last couple of emails about restocking my tank and I didn't give a complete description of what's in my tank (sorry). <No worries.> My Tank: 10 gallon AquaClear All Glass Tank Light Hood Whisper 20 Power Filter w/ Biofoam (this black foam that slips in front of the filter cartridge) Whisper 10 - 30 air pump A bubble wall An action pirate ship bubbler 10 plastic plants of different kinds (small - medium) Small fake log with silk plants attached Small Easter Island Statue Small natural color shallow creek pebbles (I think) <Sounds like plenty of great cover for the Corys to feel safe.> I currently have 4 Corydoras paleatus, 3 males about 1 inch long and a female about 1.5 inches long, look like they are doing great. I had 2 of them for a couple of months now and the other 2 for a month or 2. My tank has a regular temperature of 78 to 82 degrees and when winter time rolls around I'll drop a heater in to maintain a steady temp. The ammonia is 0, nitrite is 0, and nitrate is rising but I am doing water changes to keep it down around 20ppm. <Try to get this lower - otherwise it sounds awesome so far.> Now I would like to start adding more fish to the mix. From reading/receiving information from your site, I've narrowed my choices down to a couple fish I would like to add to my tank. I definitely want to add a couple more Corys, either panda Corys or peppered Corys, to my 4 peppered Corys. <Either would be fine, I think.> For tetras, I like Black Phantoms, Flame, Glowlights, Lemon, and Pristella and for Rasboras, I like the Harlequin and Scissortail. If I were to get panda Corys, how many would I need to get for it to feel comfortable around my peppered Corys. I'm afraid one panda Cory wouldn't school with the other peppered Corys. <Agreed; your best bet is to stick with peppered Corys, and plan some day in the future to go with a larger tank and do a same- or similarly-sized school of pandas.> As for the tetras and Rasboras, how many could I get so as not to overstock my 10 gallon tank. I learned the hard way before with an overstock of goldfish. <So many people do! Don't feel alone in this!> I know tetras and Rasboras like to be kept in a school of 5 or more. <If at all possible, yes.> Is it possible for me to get at least 2 different types of fish without overstocking my tank? I am thinking of around 5 - 7 Corys total and 2 different schools of tetras and/or Rasboras with 5 or more in each school. <I would go with the 5-7 Corys and one type of tetra or Rasbora.... And just five of those. A 10g tank just isn't forgiving on water quality once you begin to reach the stocking limits. And again, if possible, consider a larger tank in the future.... some time down the road.... to have more options.> If you have any other combinations and amounts of the types of fish I could keep I would really appreciate it! <Just as above - pick your favorite of your list (possibly omitting the Pristellas for their pretty harsh aggression) and go with five or six of those. Then in the future, when you're addicted and go up to a 29g or 55g tank, well.... the possibilities are nearly endless!> Thanks again WWM Crew! <And thanks for being such a great, conscientious fishkeeper.> Wayne <Wishing you well, -Sabrina>

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>

Up late stressing about my four Corys <Ananda here this late night/early morning, fielding the puffer questions...> I just did what now seems to be a very stupid thing. I had an overflow of snails so I read all about loaches and went to the local aquarium store to buy myself a small pack of them, having read they where a schooling fish. I was a little nervous about this and was easily manipulated by the evil aquarium experts? . <Always stick to your guns when you have researched something...keep in mind that the people at the store are trying to sell you something and that non-commercial web sites about fish generally have the fishes' best interests at heart.> Anyways they told me I would be better off buying a single Puffer fish, and after asking what fish I already had in my aquarium told me to add a teaspoon of rock salt per gallon of water to my aquarium. <Knowing you had Corydoras catfish? Shame on them!!> It has been a little over a week now and my Cory Catfish are not eating, and I just read that Corys can not tolerate salt, <Usually not well at all. I would do a 50% water change with no salt in the new water.> but I now have a green spotted puffer fish as well. <Cute and intelligent fish, requiring salt as they mature.> Tell me how to safe my fishies without buying a second aquarium please. :( <Oh my. That is difficult, because the puffer needs salt, and the Corys can't tolerate it. Very young green-spotted puffers (under 2" in length) can tolerate freshwater for short periods. But your long-term solution is another tank for the puffer.> <Best wishes, Ananda>

Fluorite and Corydoras I am planning to start a 37 gallon tank with angelfish and Corydoras. I have the plants planted in fluorite. Is the fluorite okay for the Corydoras or will it hurt their barbells? Marc <Hi, Marc - it's not so much their barbels I'd be worried about, but their soft, scaleless bellies.... Fluorite is pretty sharp stuff, and I think that is a good concern. Would you consider covering the fluorite with a thin layer of smooth gravel? If you get gravel of a slightly larger size, it should primarily stay on top of the fluorite, even when you siphon/vacuum. Wishing you well, -Sabrina>
Fluorite and Corydoras, II
Sabrina, I've pretty much decided to switch the fluorite out for Eco-Complete. <A much more 'roundy' plant tank substrate, probably much nicer on Cory bellies!> I might reserve one section of the tank for some Tahitian moon sand, too. <Do keep in mind, sand will ultimately settle beneath the Eco-Complete; you may never get a chance to enjoy it, really. Might want to think about a gravel of a slightly larger diameter than the plant substrate, and just laying a thin layer over the top.> Thanks for the help. Marc <You bet. Wishing you, your plants and Corys well, -Sabrina>

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