I'm having 5 goldfish inside a 2ft tank. currently, having problem with the waste produce by these fish... i have to clean the filters inside the wall hanging type pump.

need advise: will add a external canister will help in cleaning the water? this is because i read that it is not good to wash the filters everyday, as it will kill good germs inside it.

sorry, it is bacteria, not germs. haha.

planning to get a canister soon~ today, my 3 fish suddenly get clamped fin (or known as ironed tail in chinese). looks like my water contains too much of ammonia...

the size of my fish body is around 6cm long... my dad rear them start from 2cm since 1year ago, buyng those cheap RM1 one.

I have added one external canister, and it really makes the water cleaner... but after adding it, 2 of the fish become not active, always rest on the sand, without moving. is it due to shock, or the so called swimbladder problem??? help me....