Help!!!

[bratzoman]

I got a black fancy goldfish a week ago and put it with my other goldfishes in my tank. 4 days after that I noticed that the amonia level was high, so i invested in a power bio-filterand did a complete change of water ( I just figured out about the cycling process). The next day I tested the water and all the amonia, ph, nitrite and nitrate level are normal, but I noticed that my goldfish is laying constantly at the bottom of the tank. When I tapped the glass or open the hood door the fish starts swimming around the tank or comes to the top. Does my fish got amonia diseased or something else??? if he does, can you tell me what can i do???

[Rue]

I think you might have shocked the fish with the severity of the WC...

...fish can easily handle 100% WCs, but only if the water quality isn't too drastically different...that's why recommendations for WCs range from 10-25% a week to 25-33% every two weeks...

[cocoa_pleco]

what size tank is it?