Like almost all living creatures, fish are territorial in nature. When they are kept together in the limited space of an aquarium, careful planning is required to minimise aggressive behaviour, which can otherwise lead to unhealthy fish who will not thrive or survive in your tank.

 

Why do some fish behave aggressively?

Guarding our territory is one of life’s basic instincts: after all, humans spend a lot of time and effort in protecting and defending their property from intruders, and there are all sorts of unwritten rules around respecting boundaries and personal space. Fish are no different: territories revolve around breeding, mating, and feeding hierarchies.

 

How do fish defend their territory?

A fish will define a territory by engaging in warning behaviour, such as flashing, dancing, and extending gills and fins, and physically charge, and even direct water movement at a rival. They will try to avoid direct clashes of possible, to minimise the risk of being injured, but bolder fish will make physical challenges to a rival, such as nipping.

 

What type of fish are the main aggressors?

Generally, members of the same species will tend to fight each other for territory, particularly males, as they are more likely to have similar feeding and mating requirements. Some species are known to be more aggressive than others, such as damselfish, and maroon clownfish. Take care not to mix lots of similar looking fish together, as they will be hostile.

 

How can you minimise aggression in your tank?

As well as avoiding mixing the same, or similar looking species that are known to be aggressive together, there are a few other things to bear in mind for a peaceful and happy tank. Firstly, make sure your fish are well fed, and the food is well distributed around the tank, to minimise any risk of fighting over food.

Be aware of the sex ratio of your fish, as males will tend to fight more frequently than females over breeding rights. A single male or even an all-female group may be more peaceful than one with several males.

Make sure the habitat of tank is diverse, with plenty of rocks, corals, caves, or plants to provide shelter and make it easier for the fish to define boundaries. If a fish can keep out of sight more easily, there is less chance that clashes will occur. A tank that is too bare will leave persecuted fish with nowhere to escape to, so add lots of detail to the environment.

If you are introducing new fish into the tank, it is a good idea to rearrange any movable items such as rocks, so that if territorial fights do occur, they will all be starting on a fresh playing field rather than defending already established territory.

If you are starting from scratch with your aquarium, allow less aggressive fish to establish their territory first, before introducing bolder fish. Even with all the most careful efforts, clashes will probably sometimes occur between fish, but by following these steps, you can minimise the risks.

Ask your knowledgeable shop staff for some advice too, as they will know their stock and will have lots of experience in establishing a successful marine aquarium.

 

If you are looking for fish tank rocks in the UK, please get in touch today!