ill goldfish

Question
Hi,i would like to ask about my fish, i have two large goldfish about 6" long and just recently introduced two small goldfish, but we have now noticed that the small fish have started to nip one of the larger ones,we then separated them to a different bowl for a day but now the other large one has also started to push and nip at the other. its like he doesn't want to be near any of the fish now he drifts slowly up to the top of the tank tail first, a bit like he's standing on his head .We have had both larger fish for four years now and would hate to lose them please can you tell me if you think there is something wrong.

Answer
Hiya!

Unfortunately when you introduce smaller fish to an aquarium, even if they are the same type of fish, nipping can occur, as can bigger fish bullying the smaller fish. The bigger fish that was being nipped by the smaller fish and then also by the other bigger fish, is that the same fish that is now drifting to the top of the tank? If it is the same fish there is a chance the fish isn't well which is why both the smaller fish and then the big fish were pushing and nipping at it, fish can sense disease and illness in other fish before anything becomes apparent to us.

IF you have a 'spare' tank that you can use as a hospital tank I would recommend moving the fish that is drifting to the top of the tank to it and monitor its behaviour.  There is a chance that the behaviour it is displaying is submissive behaviour which is why it is just drifting around the tank with very little life....if its not being active the other fish are less likely to pick on it.

Another bit of advice....it is not ideal to put goldfish in a bowl even for a short period of time....despite pet stores still selling them, they really are NOT ideal as goldfish do need filtration and an air source which is why so many of them die when kept in a bowl. What I would recommend is investing in a small tank that you can use as hospital/observation tank should any of your fish require being moved....

Hope this has helped!

Cheers! Rach