I have two angelfish (one black and one zebra (silver with black stripes)) which are around 9 months old now, they are in 120lts.

They don't really spend much time together so I guess that they are both male. The silver has always been the more dominant and they would fight maybe once a week, with the silver always winning and the black disappearing to the back of the tank in submission.

Now, the black seems to have grown much bigger over the last month and things seem to have changed between the fish. For the last week or so the black wins all the fights and the silver is always at the back of the tank, only coming out at feeding time. He does try to come out but as soon as the black sees him, he chases him away. He has also started chasing other fish (something I've never seen before) and I saw him stalking a shrimp earlier!

Is this kind of behaviour and role reversal normal?

They are probably either both male or both feamle. I would take one to your lfs and get another good sized one, but if you do this, rearrange the tank when you put the new on in. I had 2 males, and one day, i came home to find one angel hiding under a rock, and the other hunting it out aggressive. So, i had to take the other one to my lfs, and then the one that was bullied died, so they can get pretty mean.

It's often a problem if you have two> best to have 3/4 if you have the room, or as has been said try and exchange one and re-arrange the 'furniture'. (There is no guarentee on whether you'll get a M/Female and bullying may occur again)

Best of luck!

This post has been edited by rossyt99: Jun 10 2008, 04:30 PM