During the breeding season, many animals, especially males, often fight fiercely for mates, especially for females to mate with. Some animals, for territory and food, often fight with each other, some fight to the death, and some just play. When animals fight, they often use bites, claws, kicks, and horns to play their own advantageous weapons.
The fight of mudskippers is different. Although they also open their mouths wide, this is just to scare each other. In fact, they use their fins to hit each other when fighting. This fighting method is not life-threatening for both parties.
