Angelfish Aggression

[Denj]

Hmmmm.... The more replies I get the more people sight the possibility of an ammonia spike as being the most likely cause of losing so many fish in such a short period of time. I've always taken my tanks water quality for granted because honestly in the 4 - 5 years I've had the tank set up I've never really had a major issue regarding water quality (that is once my tank had been established). But I'm going to have to start being a bit for diligent regarding water testing & revisit my tank set up (it couldn't hurt any, it could only help).

I appreciate you guys "drilling" this possible scenario home to me. I forces me to not just write off my losses to "fish aggression" which could prove to just be really inaccurate (hence LAZY).

AND I didn't know that corys were such voracious scavengers. I knew they were great scavengers, BUT I didn't know they'd scavenge on fish that were not fully dead, QUICK. I guess it shouldn't surprise me though. You learn something new everyday.

Thanks for the reply RiVerfishgirl

 

[RiVerfishgirl]

AND I didn't know that corys were such voracious scavengers. I knew they were great scavengers, BUT I didn't know they'd scavenge on fish that were not fully dead, QUICK. I guess it shouldn't surprise me though. You learn something new everyday.

I've seen some fairly large fish die in tanks with cories and within a few hours nothing left bone a couple of bones and very fat cories.

And yeah I've seen cories start to snack on fish that were ill and didn't look so well. It's pretty gruesome.

They're really efficient scavengers, and once it seems like they sense a fish dying they start to go to town, especially in large groups.

Thanks for the reply RiVerfishgirl

No problem.

I understand getting lazy with a tank you've had set up for a long time. But things happen that can compromise your biological bacteria, make them stop working efficiently, add excess ammonia load, etc.

One thing I would check is that your filters aren't housing a bunch of gunk, or even pieces of dead fish, or pieces of decaying plant, etc., because that will add excess nutrient load that you don't need. And if you have these excess nutrients in a system that possibly has inefficient nutrient elimination (not sure what you're setup is...but a canister filter getting clogged and starving the bacteria of oxygen is one example), it can be disastrous.
Your biological bacteria NEED oxygen and anything depriving them of it will start to de-colonize your filter or make them work less efficiently.

 

[abcdefghi]

Adding to what RiverfishGrl posted it could have been an ammonia spike simply from adding 5 angels to the tank. It sounds like all the other fish are small, and so would not contribute much to the bio load. Adding 5 angels would have increased that bio load by a fair amount, which could have led to the ammonia spike.

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