goldfish keeps hitting side of tank on purpose

[leefly]

hi we have 3 gold fish and one is way bigger and stronger than the rest and recently he has been banging in to the side of the tank on purpose really hard he then swims funny for a bit as if he has hurt him self..is is just crazy or do you think there is somthing wrong with him

[B00]

Can he see his reflection on the glass?

I ask this because fish when mating will butt the bellies of their would be partner, and I'm wondering if he's trying to butt his reflection thinking it's another goldie?

[leefly]

thanks

have you got any ideas on how we can stop him seeing his reflection we have a rectangle tank 3 walls are open and one the back wall has a background on the outside

[B00]

It might not be that- it's just a theory on my part, but worth investigating.

How about placing black card on the outside of the glass on the sides of your tank?

[sstreet]

how big is the tank it might be because he wants a bigger tank or just to get out. of corse from banging in to the side hardly would make him swim funny how long has this been happening for ? if he is always swimming like that change tanks right away !
owner of fish

[ginface2k1]

Maybe it has a parasite. Sometimes they bang against things or rub against ornaments to try and get rid of it.