I seem to have a problem with catfish...

[Mr. Pockets]

could be huge ammonia spike from removing gravel and all that jazz

I didn't remove the gravel until a week after the ripsaw incident. Also, I'm not sure why removing the gravel would cause an 'ammonia spike,' unless it was filthy and had a ton of debris that was released. I keep mine pretty clean.

I removed the gravel (about 50% of it) in hopes of reducing the risk of anaerobic bacteria in dead zones. Since I can't test for hydrogen sulfides, of course it's just a guess.

 

[Mr. Pockets]

I'm resurrecting my own dead thread, in the hopes that my lesson may save somebody else's fish.

Since new fish died within a day or two, the owner of my LFS asked me to do a very specific water test. First thing in the morning, before it got light outside, he asked me to take a sample from the very bottom of the tank. I used a small tupperware container, closed it outside the tank, opened it under water near the bottom, and closed it while it was still down there. He asked me to keep the sample in the dark, and bring the container to him in an opaque bag or box.

John ran an oxygen test on the water that day, and then another 24 hours later. A decrease in oxygen shown during the second test suggested that something was decaying in the water.

So I removed everything from the tank except for the gravel. I did a pretty big water change, and when I removed the large piece of driftwood I had in the tank, it reeked. There was a strong rotten-egg smell coming from it, so it was clear to me that something anaerobic had taken up residence. Obviously, I removed the driftwood and threw it away.

John ran similar oxygen tests on my water a week later and the oxygen remained steady in both tests. I introduced a small striped raphael as a canary, and he survived the first week test.

A couple weeks later, I pulled out another piece of driftwood I had placed in the tank, and it was starting to smell as well. My guess is that surviving anaerobic critters had found the wood and started new families.

I have since put new pieces of wood in there since, and they seem to be fine. I remove and check the wood every time I clean the tank. I keep driftwood in the tank for my royal pleco. Apparently he likes the fiber.

I have also gotten a new ripsaw catfish, and after a few weeks he (and the little striped raphael canary) seems to be doing well. He digs up all my fake plants, though. I have to replant them every couple days.

In the end, then, the problem seems to have been hydrogen sulfide. It affected new fish, I believe, because they weren't used to the poison in the water and have a much higher rate of respiration when moved to a new tank.

I hope this helps somebody else in the future.

 

[[enjoyable_attempt]]

Never heard of a case like that...