Can someone please help! I've had 8 fish in my tank for a while now, I have moor fish, goldfish etc. Recently all of the fish have been targeting the 2 black moor fish I have. They have both began to develop silver on their scales. I've found one of the black moor fish squeezed against the filter stuck the other day and the fish even attack the black moor fish in the plants I have. I don't know whether to remove the black fish for a while or permanently or is there another explanation?. When I removed the 2 black fish yesterday they did look like they were dying. Can anyone please help??