Bullying can be a problem in fish tanks, but there are things you cna do to help restore harmony to your community tank.
Add some 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; 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.