What to do with my aggressive danio?

Question

I had a betta and 3 danios in my tank. One danio was nipped to death by another, and my last friendly danio is being pushed around by the larger one. Its fins and tail are really battered, and I'm not sure if it'll live. On the other hand, I don't want to leave the aggressive danio in with my betta if it's going to kill my betta too. I need to get rid of one; which one?

Answer 1

Remove the trouble maker for sure. Find him a new home or give him away, but he's the one to get out of your tank.

MM

Answer 2

You can separate him with a divider or give him away. Another option would be to provide him with enough fish to actually school with. Danios are a schooling fish. The statement that "you should at least get three" means AT LEAST, which is the absolute minimum under ideal conditions. Schooling fish often begin to act similar to cichlids if they are unable to school, which means lots of fin nipping and chasing. If you are able to keep ammonia, nitrite, and nitrate down through water changes, then try 6 or more danios to go with the bully danio. Danios have very little body mass and will not be a big load on the bacteria as long as you are smart about feeding and siphoning. Do plenty of water changes, include a real danio school, test your water, go light on food, and you will have success.

Answer 3

I got a little fabric mesh box at a pet store for one of my fish that was a bit aggressive. It hung from the top of the tank down into the water. After several weeks in "isolation" he was ready to return to the aquarium community as a reformed citizen.

Answer 4

I think I've seen plastic dividers you can put inside your tank to isolate aggressive fish from others in the tank. You might check with your aquarium supply store and see if such a thing is available.