The most common reasons why betta fish fight are: Territorial aggression - Male betta fish are known for being highly territorial. They will often fight other males entering their territory to protect their space. There are so many variations that betta fish are usually classified by their colors, patterns, and tail type. Their aggressive behavior is often off-putting for newcomers to the hobby. However if properly fed and cared for, you shouldn't have any problems. While betta fish aggression can vary from individual to individual, some betta fish species are generally more aggressive than others. Here are a few examples of betta fish species that are known for their aggressive behavior: Wild Betta Fish (Betta Splendens): This is the species from which all domestic betta fish have been bred. However, in general, crowntail bettas are known to be more aggressive than other types of bettas. This is likely due to their high level of energy and their territorial nature. If you are considering keeping a crowntail betta, it is important to be prepared for a more active and potentially aggressive fish. Wild Betta Species are generally more aggressive than their domesticated counterparts. In the wild, they live in tight-knit groups and compete fiercely for resources, such as food and mates. This aggressive behavior is often seen in Bettas when they're kept in captivity. Male betta fish tend to be more aggressive. They set up territories that they defend with their lives. When another male betta is introduced into the tank, the original male will start to display warning signs. These warning signs include flaring their gills and spreading out their fins in an attempt to make themselves look like a serious threat. .

which betta is more aggressive