Why do fish chase each other?

If you have a fish tank filled with multiple fish, there are probably many different behaviors that leave you scratching your head. From their eating habits, hiding, swim patterns, as an owner you probably have a lot of questions as to why fish do things a certain way. Another common behavior among fish is to chase each other around the tank. Are they mad at eachother, are they just playing around, are they trying to mate? We are going to discuss this behavior in today’s article, and explain what motivates fish to do this.

Why do fish chase each other around the tank?

The main reason fish chase each other around the tank is because they are playing around, they are aggressive, they’re marking their territory, or they are mating.

Playing around

Most of the time, fish chase each other around because they are just trying to have fun. Imagine their fish tank as a jungle gym, and the fish are just two little kids chasing each all around. It is basically like two kids that are just playing tag with each other. When fish are chasing each other in a playful manner, it usually doesn’t last as long, and they are not biting or being aggressive with one another.


Another reason fish chase each other around the tank is because they are aggressive and want to fight. This is very common when two fish of different species are fighting each other. This is very common in fish tanks where there are species of aggressive fish. When they chase each other around, it may continue for a long time, and there may be some nibbling involved. This is very common in fish tanks where there are many different species of fish with different personalities. Your fish might also become more aggressive with one another if you are not giving them enough food. They will start to fight and chase each other during feeding time to get as much food as they can. Aggressive behavior is also common in fish tanks that are not very big, because the fish are forced to be in close quarters with one another and share different areas. 

Claiming their territory

While it may be hard to tell, fish are very territorial animals. Whether it’s the castle ornament, the rock, or sometimes even a plant, fish feel entitled to their territory and will do anything to protect it. If another fish comes near their territory, they might chase it around to let it know that it should not come near its territory. The fish usually won’t chase the other too long, just enough to get the fish away from its territory. 


Chasing each other around the fish tank is also a very common behavior when 2 fish are mating. Of course, this is only the case when the two fish chasing each other are of the same species. Fish that are mating will calmly chase each other around the tank before mating. You can view it as a form of mating. When they are chasing each other, it will usually not be very fast, and not in an aggressive manner.

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