Sick corydoras

[Saphira19]

I have 4 corydoras - 2 pairs, 2 peppered and 2 albino in an 180 liters tank, together with 2 ancistrus, 5 SAE, 10 werners, one otto and about 20 neeons. I have had the corries since they were young, 3-4 years ago.
4 days ago I found one of the peppered ones (the female) laying on the bottom belly up. First I thought it was dead, but realized its gills were moving. I tried to poke her up, but she laid there. For 2 days I have lifted her in a net close to the water surface and tried to give her some food - sadly without success. There is no improvement, and I think she is just starving, as her stomach gradually sank in, and it breaks my heart to see her like that. She follows my movements with her eyes, as corries do, but other than that and fin twitching, she doesn't move at all. I tried treating the tank with a general medication - which I used in the past whenever one of my fishes looked a bit down (Multicura from Easy Life), but no improvement has happened. There are no other external signs of sickness that I can tell. I asked on couple of forums if there is any treatment, but got no answer. Right now I am considering putting an end to the poor fish misery - I read about clove oil though I never had to do that to a fish before, but I am asking here as a last hope.

As I assume you will ask me about water parameters, currently I only have some of those sticks sets from Easy Life, but they don't show anything out of the ordinary - ammonia and nitrites 0, nitrates around 20-40. The tank is heavily planted, setup is 2 years old. It has 2 external filters - one Eheim 350 professionel and one JBL e700. It has co2 and I dose fertilizers by an automated pump according to producer's label.

I did have some new additions to the tank recently: 3 ottos, out of which only one seems to have survived sadly (ordered 5, 2 died during transportation, 2 more after about a week) and the werners. Since I heard ottos are wild caught, I'm wondering if they could have come with something nasty. None of the other fish seem to have issues.

 

[SeanTrollope]

dont give up hope you. i am going to suggest doing a 40-50 % water change and go and get a proper test kit.

 

[Byron]

Diagnosing a specific issue causing fish illness/death is often extremely difficult and sometimes impossible if one is not a biologist. But I will offer a couple of general suggestions.

A significant water change is often beneficial. The fish may still not make it, but the therapeutic value to the other fish from this cannot be overstated. Use a good conditioner, but no other additives. Everything added to the water gets inside the fish naturally, and when something is wrong there is already stress present, and increasing it is not going to help.

Second, I am not a fan of "catch-all" medications which again can often do more harm than good. I looked up Multicura and it is discontinued, replaced by Voogle. I cannot see what possible benefit this could have, either generally (they recommend using it continually) or as treatment ("plant extracts" ??).

"Werners" I assume is Iriatherina werneri, the threadfin rainbowfish. "SAE" are Siamese Algae Eaters? If so, they get to six inches and can be boisterous, and this is only a 180 liter (50 gallon) tank. Have you noticed any interaction between these and the cories?

Otos frequently arrived nearly starved, and many die soon. This is due to their diet of algae that is noty available during transport; the tank should contain algae or they frequently don't last. As for other disease, any fish added to an existing aquarium is a risk for disease. In my experience of several years, commercial hatchery-raised fish are far more likely to carry disease than wild caught imported fish. But it is obviously still possible. Quarantine all new fish for several weeks, there is no other way to avoid serious risk of disease.

Nitrate over 20 ppm is not good for fish, and cories are very sensitive to all forms of nitrogen (ammonia, nitrite, nitrate). This is not likely to kill them outright, but it does weaken them, which only makes other issues more dangerous. With plants in the tank, nitrate should be much lower. Do you have nitrate in the source (tap) water? Or are you adding nitrate as plant fertilizer?

Byron.

 

[Saphira19]

I know diagnosing is difficult, especially in this case, when there's no outer signs.
I will do a water change tomorrow, was due on Sunday anyway, but I was on an intensive course and been super busy with work ever since. As general information, I do 25-30% water changes weekly.

I heard Multicura was discontinued, I don't think Voogle is the replacement, they existed in parallel and as far as I know, Voogle is just some kind of conditioner/booster. Multicura was recommended to me by hobbyists here as being a gentle product. I have used it every time I spotted minor signs of disease (saw once or twice signs of ich) - but I tend to take measures at first symptoms and I had no major issues with it. I also used preventive, when adding new fish, as they say in the prospect. It turns water green, which makes me suspect it's got some malachite green in the composition (hope that's the correct english name).

I know quarantine tank is the correct way, unfortunately I don't have one. In my defense, if I'm allowed, I very rarely get new fish - the ones I mentioned were the first ones I got in the last 6 months, and the SAEs were the only others that are less than 2 years with me (the age of the setup). I got them after donating my guppy "collection" - as they were constantly an issue with over breeding and I was tired of looking for people to donate them.
I know SAEs get big. I got them to deal with a case of bba - and they did an excellent job of it.
I forgot to mention the tank also houses a fair amount of shrimp - RCS and Amano. You were correct with the Iriatherina werneri. I was somewhat anxious about them, as I have read that rainbow fish are pretty shy, but they were the 2nd reason I got rid of the guppies (I really wanted them) and they somehow seem to get along really well with the neons (they sort of school together). Just to be clear, "getting rid" of them means donating.

To answer your question, I did not notice any interaction between the corries and the others. 3 of my SAEs are small (like 4 cm long), 2 are older (like 7-8 cm) - they're not very common here and I got them from different sources, knowing they like to be in a group. My ancistruses are bigger (like 12 cm long), and they sit with shrimp walking on them - they also used to get swarmed by guppy babies when I had them. In fact, my corries were more visible and playful after getting rid of the guppies - as the tank got a bit quieter (if you can say that about fish). I have never noticed any sign of aggression in my tank.

I knew the risks when I got the ottos, I know they often don't survive. My tank has decent amount of algae (I actually had a minor outbreak of spyrogira when I got them), I'm not one of those people that like a squeeky clean tank, just to keep things under control. I don't dose stuff like excell (it's under a different brand here, but same shizzle).

I am adding nitrate as fertilizer. I have not changed the product recently, but I did get an automated liquid dispenser pump, as due to schedule issues I was fertilizing weekly or by-weekly and tended to be rather chaotic about it. the pump dispenses small amounts daily rather than me dumping a weekly dose. I did not notice higher values of nitrates after installing the pump. I just decreased the dose by 30%.
I'm adding a picture of my cory, taken today. It looks like it's sort of lumpy but that's just because it was in a bit of a weird position when I took the picture. The fish has a normal shape, no swelling or lesions, but her belly sank in in the last few days.

 

[Byron]

A couple comments from your latest data (thanks).

I would do larger water changes; I do 60% or more on my 8 tanks once a week. Most important, and this helps fish remain stronger. The nitrate is a concern, it should not be as high, so I would look into that. My planted tanks run between 0 and 5 ppm and have for 15+ years since I tested them which I now do periodically. Nitrate is toxic to all fish, it just depends upon thee exposure and the level.

The EasyLife site says Voogle replaces Multicura. But I would not use either regardless. I really cannot see a benefit, and this stuff, whatever it is, is getting in the fish's bloodstream and internal organs as every substance in the water does, and at the very least this is not "natural."

I won't guess as to the cory issue; it seems doomed to die and I would let it. I rarely, which is to say basically never, treat individual fish unless I can bee fairly certain the issue is likely contagious. Unless you know the issue, treatment is hit or miss and usually the latter. From what you've posted I wouldn't suspect this is a contagious issue.

 

[Essjay]

I am adding nitrate as fertilizer.

This could be why the nitrate level is quite high.

 

[Saphira19]

I did a 25% water change now and I'll do another tomorrow. I've always been advised to keep nitrates over 20 here. I took a picture of the tank while filling it up, it's not been pruned for 3 weeks due to lack of time so bit messy, usually I keep it "shorter".

 

[Byron]

I did a 25% water change now and I'll do another tomorrow. I've always been advised to keep nitrates over 20 here. I took a picture of the tank while filling it up, it's not been pruned for 3 weeks due to lack of time so bit messy, usually I keep it "shorter".

Very lovely plants and tank.

I understand about the nitrates, but that is a case of providing more for the plants at the expense of the fish. I tend to think in reverse, so my plants have to manage for the benefit of my fishies. Nitrate of course is the additional nitrogen for the plants. Most aquatic plants prefer nitrogen as ammonium, which is why they rapidly take up the ammonia/ammonium produced by fish, decomposing organics, etc. Plants turn to nitrate when ammonia/ammonium is insufficient for their needs, but they have to change the nitrate back into ammonium before they can assimilate it as nitrogen. This uses energy so the plants only do this when ammonium is lacking. No one is going to suggest dosing tanks with ammonia/ammonium with fish and invertebrates present, so nitrate is deemed the safer option. But nitrate is still toxic, just as ammonia and nitrite are, though it takes longer to kill the fish depending upon the level and exposure. And most sources will now advise keeping nitrate below 20 ppm, and as low as possible.

 

[Saphira19]

Ty for the kind words and for the advise, I will pay more attention from now on. I already lowered the daily dose by 30% and I will monitor the levels in the coming days. I'm really sad about my corry, she's been in my tank ever since my tank-mania started and I wanted a good long life for her. I don't have high hopes at this point (or much at all), but I will wait another day to see if anything changes. I'm sorry that I had to learn by mistakes.

 

[Saphira19]

Unfortunately my fish has not given any signs of recovery and I think at this point it's only torment for her. She hasn't eaten in more than a week, and other than occasionally thrashing on the bottom, she only lays on a side. The other fish don't have any signs of sickness.
I've read about clove oil/vodka euthanasia, but I'm a bit confused:
- is clove oil a specific chemical product or is it essential oil from cloves? I bought essential oil.
- some articles mentioned that you can do it only overdosing clove oil, others that you also need to use vodka. Which is it?