Help! My fish are dying!

I don't know what's going on in my tank. Tonight I found two dead cories and a dead angel fish. The cories have been acting kinda funny lately, kinda slow, sitting around and hiding a lot, but the angel fish had absolutely no problems that I had noticed.

I added some driftwood a couple weeks ago that I bought at a LFS, could that be a problem? They said it was for aquariums, plus I soaked and boiled it before I put it in the tank. I took it out tonight, just in case it's the problem.

All the levels (ammonia, nitrites, nitrates and ph) are fine. I change about 20% of the water once a week. Nothing has changed in the tank recently, except I added some ghost shrimp about a week ago.

What do you guys think? I don't know what to do and I don't want to lose anymore fish! This really sucks.

Thanks,
jen

Ammonia and nitrites are zero, nitrates were between 10 & 20 ppm before I did the water change. I tested again this morning and it looks like it's still about 10ppm. Is this too high? Could the nitrates be the problem? The ph is usually at 7.0, but this morning when I tested it, it was at about 6.8. It tested at 7.0 the whole time the driftwood was in the tank.

What should I do? Just keep doing water changes? Should I add any medication or salt or something?

Thanks,
jen

I forgot to include the temp. It's about 80 degrees.

Originally posted by OrionGirl
Seems unlikely that the wood contributed to any problem. That leaves disease, or pre-existing issues. Any signs on the dead fish? Discolorations, gill damage, etc...Any other behavioral changes, other than lethargy?

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Besides lethargy, the fish looked fine while they were alive. The angel fish wasn't even lethargic, last time I saw it alive it was swimming around, just like it always does. They cories were the only ones I was worried about; finding the dead angel fish was a shock! The bodies were in really bad shape - missing eyes and fins, just all chewed up. It was the smallest angel fish that died. At first I thought maybe the other two killed it, but I've never seen them show any sign of aggression and that doesn't explain what happened to the cories. Maybe they caught something from the ghost shrimp? The two remaining cories look ok, they're not as lethargic as they have been and I don't seen any physical problems - no spots, discoloration, torn fins, nothing.

I've had the tank set up since the begining of January, and this is the first time I've had any hint of disease or problems!

Do you think it's ok to put the driftwood back in the tank?

Thanks,
jen

It could be the angels, but I've never seen them harassing or even paying much attention to any of the other fish. I have a pair of guppies and eight tetras that hang around the same area of the tank as the angels and they don't seem at all intimidated by them. I would think the angels would be more bothered by the tetras then the cories? Maybe they pick on the other fish when I'm not around? Whenever I'm in front of the tank, the angels stay right in front of me "begging" for food.

Thanks for all your help, OrionGirl.

-jen

I just thought of something. Could the pleco be killing the cories? He's a common pleco, probably about 4 inches long. Maybe the two angels took out the annoying, little tag-along angel and the pleco has a problem with the cories?

I'm going to keep a closer eye on those angels! Do you think any of my other fish are in danger? Besides the cories, tetras and pleco, I also have two male dwarf gouramies and a farlowella. Should I put the last two cories in my 27gal tank? I really don't want to lose anymore fish.

I wasn't really interested in breeding the angels before, but now I think it might be kinda fun. I'll have to do some reading on it!

Thanks
jen