Fighter Cats - Try Not To Laugh By Watching These Videos

Cats are territorial animals and often fight to defend what they believe is their territory.
But they can also fight living together, often they start playing and this ends up in a fight.
It is also common to fight with other species, when they feel uncomfortable with the presence of other animals.
Cats, even domesticated, still retain a wild instinct, some are aggressive and express this aggressiveness by fighting.