Why are all my fish huddling together?

[Dsudnick]

I just cleaned my tank and now all of sudden all my fish 8 tetras, 2 angelfish, a little mini red tailed shark, and a beta, are all “schooling” together. This can’t be right?

 

[TheAvs21]

There could be other reasons I'm unaware of, but I have had all my fish in a tank huddling in the same spot all together only once and it was because I had large amounts of ammonia. How did you clean your tank and can you test your water?

 

[Dsudnick]

There could be other reasons I'm unaware of, but I have had all my fish in a tank huddling in the same spot all together only once and it was because I had large amounts of ammonia. How did you clean your tank and can you test your water?

I used one of those siphon vaccuums, I have a 55 gallon tank and took about 15 gallons out refilled it (treated the new water before I refilled it) and then maybe an hour or 2 after they were all huddling together. But I think they stopped. I’ll by a test kit tomorrow