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FAQs on Pygmy Corydoras Cats

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Corydoras habrosus

Corydoras hastatus

Corydoras pygmaeus

Pigmy Corys, hlth.   5/9/11
Dear Crew
I was sold six Pigmy Corys a few days ago but only four have survived. I asked if they would be ok in my tank conditions and was told it would be ok. After doing some reading, I think I might have been mis-informed as they like soft water, right?
<They do, but should adapt to "London Tap" style hard water if other conditions are okay. On the whole, Corydoras are not fussy.>
My tank is 100 litres, ammonia 0ppm, nitrite 0ppm (although had a slight spike on the day after I got them), nitrates 5ppm, PH 8, London water (hard). I used a slow acclimatisation method over an hour before I put them into the tank.
Would the hard water condition have killed them or the nitrite spike?
<The latter, with previous starvation in the retailer's tanks likely the contributing factor. Well-fed Corydoras pygmaeus are fairly undemanding.
Corydoras hastatus and Corydoras habrosus much the same.>
Thanks, Patrick
<Cheers, Neale.>
Re: Pigmy Corys   5/9/11

Thanks Neale
oh dear, bad day - lost my newly hatched Pseudomugil furcatus fry after three days (so tiny!) - perhaps he was too small for my Microworms.
Also, I think there is only one Pigmy Cory left out of six - and he has a little pink patch on his side.
<Oh dear.>
The tank now reads 0ppm nitrites (was about 0.1-0.2ppm despite water changes for a couple of days). My suspicion as to the sudden nitrite spikes now rests with the road works they are doing outside our flat - each time they return to work, we get this problem so it might be disturbing the water pipes?
<Ah, yes, I can see why this might be a worry. Not much you can do save waiting until the workmen leave. Do avoid doing water changes when they're about. Drinking water should of course be safe, so the risk shouldn't be that great. But who knows for sure? In any event, the non-zero nitrite level could indicate other issues, so do be open minded and review the aquarium. Don't add new fish for a month or two'¦ see what happens during this period.>
I just wanted to check one other possible cause of the Pigmy Cory loss - also in this tank are 6 female guppies (large!), 2 platies, 7 split fin blue eyed rainbow fish and 1 male dwarf honey Gourami. Could they be causing problems? I've not seen anything.
<No obvious problems here save differences in water chemistry, temperature requirements. London Tap isn't the ideal thing for South American and Southeast Asian fish, so review and act accordingly when shopping.>
thanks Patrick
<Cheers, Neale.>

Corydoras habrosus - substrate   11/21/10
Hello there,
I am planning to include C. habrosus in a (future) planted tank. I've been trying, without luck, to research the Rio Salinas in Venezuela which I believe is C. habrosus' natural habitat. Like I said, I haven't had much
luck. Do you know what the substrate is?
<Throughout most of tropical South America, river substrates tend to be some sort of quartz sand, and smooth silica sand makes a perfect substitute. The contrast between the tea-coloured water and the bright sand is one of the most striking things about these South American rivers.
Obviously, there's variation, with some rivers have deep silty substrates, and many have thick layers of leaf litter on top of the sand, species such as Whiptails being specifically adapted to such habitats. Around rapids and in shallow streams, pebbles or boulders may be common. It's really your choice of fish that will determine the biotope rather more than the rocks or sand; for example Corydoras would be associated with sand, Anostomus with boulders, and Whiptails with leaf litter.>
While researching, I've gotten confused with all the info and opinions about sand, play sand, pool filter sand, etc. vs. a planted aquarium substrate like Eco-complete or Fluorite. While I'm interested in keeping
plants, my first concern is the health of the fish.
<Good. To be honest, the choice of substrate is relatively unimportant when growing plants. While sandy substrates are certainly better than plain coarse gravel, the difference between an expensive fluorite sand and plain silica sand that's been improved with fertiliser tablets is trivial.
Lighting, and to a lesser extent CO2, are far more important.>
I have found CaribSea's Instant Aquarium line and really like their chart which lists size and suitability. Sunset gold has grain sizes from .1 - .4 mm and is rated as "soft belly safe". Is this appropriate?
<Yes, "soft belly safe" substrates should be ideal for Corydoras.>
Thanks for your help,
<Good luck with your project! Cheers, Neale.>

How to rescue some Corydoras hastatus  12/18/07 Hello Crew Members, <Amanda> I hope whoever answers this is having a fine day, and that it isn't as horribly hot and humid there as it is here. <I wish it were... am tired of the cold> I hope I give you enough information to help me. Any additional information you need, please let me know and I'll get it for you. As per my usual bleeding heart self I just came home two days ago with yet another sad animal case (this goes with my two one-eyed quail, deformed ring-neck, abuse rescue dog....just to name a few). To set the scene. I was visiting a friend when their brother came over for a visit. He was going on about this fantastic new fish tank he had bought for a bargain price (at this point I'm thinking sweet!) the only catch was that it came with fish included....this always seems to be where the problems start. He didn't like any of the fish, and instead of doing the responsible thing and taking them to a shop and selling them, he got the fantastically brilliant idea (this being said very sarcastically) of just not feeding them until they died and then he could go out and get the fish he wanted. <Terrible> I of course was absolutely mortified by this. I asked him how long he'd had the tank, he didn't remember, for at least 6 weeks he thought. I'm thinking poor fish, how about I lock you up in a tiny little room you never asked to be put into and then not give you any food for, oh somewhere around 6 weeks, and see how you like it....actually I probably said this all to him while getting increasingly upset as my face went redder and redder and I backed him into a corner pointing my finger and going on some tirade about animal cruelty and people like him needing to get what they deserve etc..... So I am now the owner of 5 Corydoras hastatus. There were 7 when I first got them 2 days ago. The first one died within 2 hours, it was pretty much done for when I picked it up, but I just didn't have the heart to leave it with him. Even though I knew it was going to die, I wanted it to at least die in clean water. The water they were in was filthy, I don't know how they were still alive. Ammonia - .5, Nitrite - off the chart, Nitrate - off the chart, pH - so low they might as well have been swimming in vinegar (somewhere around 4.8, I checked this on 3 different test kits) and the water was at about 34 C. The second one died this morning of what I think was Septicaemia (his abdomen was bright red with this spreading out into its fins lightening to a pinky colour). 3 of the remaining 5 also have less severe cases, again of what I believe to be Septicaemia. They are quite tiny, only about 1.5 cm (although I think I read that they only reach a max of about 2.5cm) so it is quite hard to critically examine them, but they appear to have intact fins and barbells (which I am taking as a positive sign that I may still be able to save them). Will just providing them with much improved water quality fix the Septicaemia? <Yes, likely so... but do the improvement slowly... over days, weeks time> I really don't like medicating so would prefer to avoid it if at all possible, but I will if you think that will help them. <I would just improve their world> I currently have them in a 45L tank. I have tried to find information on WWM about hastatus, but there doesn't seem to be much. <Not much on the Net compared to what there is in print re Corydoras, Callichthyids> I did see one post where it was indicated that they shouldn't be kept in a tank of more then 30cm depth, but it doesn't say what size the tank should be capacity wise. Is this tank size too small for them? Too big? <Is fine> Just right? I know that many Corydoras are temperate species and don't tolerate high temperatures well. Is that the case with this species? I currently have the house air-con set at 25 C and a heater in their tank set at 24 C. Is this an appropriate temperature for this species or should they be kept in warmer water (closer to 28C)? <See Fishbase.org re... is fine as well> My next big problem with them was the pH. I know you shouldn't change pH quickly as that can put the fish into shock. But I also know that a pH of 4.8 is WAY too low. I'd be much happier seeing them at a pH of closer to 6.5-7. I adjusted the water in the tank I was putting them into to a pH of 5, slightly higher then what they were in but not too much that I would shock them (or at least that was what I was hoping). I then gradually added water to the bag over a period of 2 hours to try to semi-slowly acclimate them to the new pH. <Best to do this more slowly... through water changes, dripping in new> I took filter media from one of my mature tanks and put it in the filter on the tank I have them in only I think the drastic pH difference has probably killed the bacteria off, so I've been doing 50% pH adjusted water changes twice a day just to make sure I don't get any ammonia/nitrite/nitrate issues. The poor little things have enough to deal with without adding foul water on top of it. After 12 hours of being in the pH 5 water I slowly raised the pH through water changes to 5.2, and it is now currently sitting at 5.4 (approximately 48 hours after having put them in their new home). Am I raising this too quickly for them in their weakened state? <I'd not change more than a tenth of a point in a day> Now food. They don't seem to recognise anything as food. I don't know if this is because they haven't eaten in so long they are too far gone to save or I'm just giving them something that they are recognizing as food. I have 5 larger specie of Corydoras in one of my other tank and I feed them a mixture of frozen blood worms, a high quality sinking shrimp pellet and occasionally some chopped up frozen Mysis shrimp. Those 5 are healthy and occasionally spawn, and are constantly cruising around the bottom of the tank browsing for food. These hastatus all huddle in one corner together they don't nose around for food and nothing I've presented them with has seemed to spark their interest. Should I try some black worms? Or is there some type of food which is irresistible to Corydoras, almost guaranteed to make them eat? <Better to just wait, leave some of the prepared food in... though a few live blackworms are advised> I really want to give them the best chance I can for them to get better. Any information at all you can give me to add to what I'm already doing or for me to change anything that I might be doing wrong would be greatly appreciated by me, and I'm sure the hastatus. They really are quite fascinating little fish. It would be fantastic if I could get them rehabilitated and breeding for me. Thank you Amanda <I wish you life. Bob Fenner>

Looking For Pygmy Corys   6/27/06 Hello crew, Where can one obtain a pygmy Cory in America? The links I have found are only in the UK. Thanks in advance, Lisa S. Immarco <They come in to the US. I saw some at a wholesaler a few weeks ago. They are very inexpensive and so not too many breeders work with them. Check out Aquabid.com or try the chatroom at planetcatfish.com.-Chuck>

Sick Corydoras habrosus... no useful info.   6/3/06 One of my Corydoras habrosus is sick. She is extremely pale and can barely shuffle along the substrate, dragging her belly. She is interested in food but can't get in position to eat with her tail up and head down, so she can't eat. Her barbels point inward instead of outward. She is winking and looking up and down more than usual. One time she actually got up to the surface for a gulp of air, but to do it she had to zoom around and around in rapid circles spiraling upward, and her body was canted over at a slight angle to one side while she did it. Got any ideas what this is and how to treat it? Should I isolate her? All the others look and act absolutely fine. <... what re the set-up here? It's history of operation? Water quality? Foods/feeding... Bob Fenner>

Mini Cory capacity  - 04/19/2006 Hi... <Tom with you.> How many Corydoras habrosus can I keep? I have a 5.5 gal tank, 2 mos. old with 7 habrosus, and I want to keep this a species tank (and I have no room for a bigger tank). <I like your thinking on keeping a species tank. A good plan for these little critters.> I have an Eheim Liberty filter rated for 20 gallons (the fish love the current) and a jungle of live plants (I keep about 1/4-1/5 of the substrate clear of plants and there is a small flat rock in the center of the clearing). <All sounds quite good...> Since the cycle finished, the ammonia and nitrite have stayed at zero, and the nitrates have not gone above 5 ppm but are usually at undetectable levels. I do a 20-40% water change weekly and use that occasion to siphon up plant detritus. <Excellent! You could give lessons. :)> I have decided there are just too many plants, so I am going to remove some. The remainder that will stay in the tank will be 3 Anubias nana, 3 Betta-bulb no-name Aponogetons, 2 banana plants, 3 smallish bundles of Java ferns, a few small stems of elodea, and about 20 Frogbits. Apart from the fact that there currently are too many leaves and banana plant stems and Aponogeton flowers tangled everywhere, the fish seem very happy and healthy even though I do tend to overfeed them. <Your water parameters don't indicate that you're overfeeding and the fish aren't complaining...> So how many total habrosus do you think this tank can carry, considering the high filtration, plant density, and good water numbers? <A good question. Translation: You've just handed me a "hot potato". In your care, very specifically? I'd say you could possibly double the number of these Corys in your tank. Answering this question for the average hobbyist? I'd feel it prudent to tell you that you're "maxed out" at seven, or eight, in a 5.5G tank.> Habrosus seem extremely clean and I've seen tiny poops lying around only maybe 4-5 times in 2 mos. The kicker is that I have to order them in batches of 10, which as you know can be as many as 12 in reality. (I have 7 only because the box got delayed in transit.) <Is there a reputable LFS near you that can place a "special order"?> So here is my thought process: Can my tank easily handle another 12 right now, because with Corys the more the merrier? <Not what I would recommend. Good Lord willing, you'd get 12 healthy animals and that would be too many for this size tank.> If not (which is what I suspect) then what about when I get natural attrition in a couple of years, how few fish should I have before I order another box, because I don't want the survivors to be stressed from being lonely? <12 to 14 would be "tops" in my opinion. Without trying to be the proverbial "wet blanket", more harm than good is occasionally done when an aquarist feels that his/her fish needs a friend or, friends. Better to under stock than overstock.> I really don't want to crowd this tank, and my reading suggests that for Corys the lower the nitrates the better... but it would be nice to get a sense of how soon I can order another 10-12. Your thoughts on the maximum total number? <Once again, I would recommend finding a reputable store that can order a specified number of fish for you. My best to you. Tom>
Re: Thanks, Tom Re: mini Cory capacity
 - 04/23/06 <<Tom>> I appreciate your detailed reply. I truly needed to get an experienced person's perspective on this. These little guys have completely exceeded all my expectations for how much fun they'd be to watch and I really want to keep them happy and healthy, so thank you! <<Glad to help. You've made this both a challenge and a pleasure by being so attentive and conscientious about your pets. My best to you. Tom>

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