It is not good when the fish in your aquarium begin bullying or fighting each other. Fish fighting can result in wounded fish, and can place stress on some of the fish. Stress can result in unhealthy or even dead fish, as they may fail to gain access to food because of the fighting and bullying.
Fish can fight for a number of reasons including territorial issues, and wanting possession or control of a certain area or corner of the aquarium. Fish fights can also be common during breeding time when fish may try to protect eggs or recently hatched young ones. Fighting for territory is common if the fish are overcrowded and feel like they need some breathing space. Therefore it is very important that you provide proper housing and population regulation of your fish so that they have enough space to avoid this aggressive behaviour. You may have to consider increasing the size of your tank or choose to get additional tanks to separate the fish.
Sadly, sometimes some fish species just do not like each other and they will continue fighting, regardless of the circumstances. If such a scenario occurs, separate the fish into different fish tanks or aquariums. In cases when fish are fighting because of food shortages, it is important that you increase the quantity of food fed to your fish. The fish may need more food as they grow, so keep in mind that the amount of food that was sufficient a few months ago may no longer suffice.
It is common that a lone species in the tank will prove to be the bully. Maybe it’s because they are unable to interact with the other fish and resort to bullying and fighting. This can be overcome by introducing additional fish of the same species into the tank. These new additions will act as distracters to the bully or will captivate their attention. As a last solution you can choose to quarantine or isolate the bullying fish from the rest of the species.
One possible solution to deal with fish fighting each other would be to introduce more hiding spaces for the fish. This can be in the form of more plant species which can provide cover for the weaker fish. But this is recommended only as a temporary measure, as hiding does not relieve the stress acquired by the fish.