Previous Questions

One of my fish is bullying its mates. What should I do?

Add plants or ornaments

If you have no plants or ornaments in your aquarium, then it is a good idea to add some. These will offer shelter and hiding places for the fish that are being bullied. It also helps to separate areas of the tank. 

Check that your fish are compatible

You should also check that the fish in your aquarium are actually compatible. If only one fish is being bullied then it could become a problem, because it will become very distressed and vulnerable to disease. However, if one fish tends to chase all the other fish in the aquarium, then it should not affect any one fish too badly. However, if a very aggressive fish is causing problems then it may have to be removed and put into another tank on is own.