Fish fight usually lasts for about 3-7 days, and then it won't be fought. The reason why they fight is that fish have a sense of territory, so they will fight for territory, but this kind of fight will not go on all the time. Once one party loses the war, it will lose its fighting spirit, and when the territory belongs, the fish will not fight. However, there are other reasons for the fish to fight again.

1. Fierce nature: Fish usually fight because of their fierce nature. Carnivorous fish, such as arowana, tiger fish and map fish, generally like to fight, but herbivorous fish rarely take the initiative to provoke other fish, and some smaller fish are gentle and hardly take the initiative to fight.

2. Oestrus: In addition to fighting caused by fierce nature, fish are also easy to fight during oestrus. This kind of fighting is usually for mate, so they will fight with the same kind. Sometimes, some fish will become fierce during estrus, and any fish close to them will be attacked by it. In this case, it is best to isolate them.

3, narrow space: As mentioned earlier, fish have a certain sense of territory, so they will fight. If the breeding space is relatively narrow, the fish may offend the fish with territory and fight at this time, so it is best to prepare a larger fish tank so that the fish can have their own space for activities.