Within the species, individuals can fight one against the other for different reasons, from food or shelter to social hierarchy or mating rights inside a group.

In the case of a conflict between different species, the fight is determined by the antagonism between those species, like competition in the case of hyenas and lions. But even so, in nature these fights are rarely seen, as just one fight for establishing the hierarchy sets it all. Still, for their own pleasure, people have organized fights between captive wild animals or domestic animals even from ancient times.

In antiquity the "shows" offered in the roman arenas were famous, true carnages organized between people (gladiators) against animals or animals between them.

Lions, tigers, leopards, bears, wolves, dogs, wisents, aurochs, elephants, bulls, hyenas, rhinos, hippopotamuses were sacrificed for the enjoyment of the public, but especially for strengthening the prestige of an emperor or patrician. But let's see some more contemporaneous fights.

After the colonization of Iceland by Vikings, these people brought to the remote island the famous Iceland ponies and the island discovered the vogue of the pony stallion fights. The fiery ponies fought violently, assisted by their owners, who were not allowed to touch the enemy horse, being themselvesexposed to the deadly bites and hoof kicks.

Pony fights are also traditional in Korea. In Anatolia (Turkey) and Afghanistan camel male fights are organized. The combatants cross their necks and the most powerful makes the other bend his neck. Sometimes the result is a draw and only a judge establishes the winner. Each owner has his strategy and pushes his animal to fight.

These fights are considered a tradition, which implies organizing real feasts to show with pride the beauty of these animals and gather money for social works.

The entrance of camel caravans in a village is accompanied by fanfare music and a fighting camel male can cost up to 20,000 Euro.

In many areas of the Globe (Latin America, Southern Asia, occasionally in western countries) cockfighting is very much appreciated. In these fights special breeds are involved, the so-called combatants (like the American Game Fowl). These birds are not especially heavy but rather have a violent temperament.

The fighting roosters are endowed with metallic spurs (more effective, of course, than the natural ones). The fight is bitter and bloody, and bets are made around these fights.

In some countries of southeastern Asia fights between the males of Siamese fighting fish (Betta splendens) are appreciated. The fighters are first put in close tanks to see and provoke reciprocally. Meanwhile, the fish change colors into splendid hues and bets start. Subsequently, the rivals are put in the same tanks and they will fight till death.

Throughout time (from Antiquity, the Middle Age and till now) perhaps the most fashionable fights have been the dog combats. Usually, these fights involve specific breeds (the most known current breeds being the Pit Bull, Pit Bull Terrier, Mastiffs and Bulldogs) and dogs are trained with cruelty. Sometimes the dogs are put to fight against wolves, bears, bulls, lions and so on, all accompanied by bets.

These interspecies fights can be even more disgusting, as in Pakistan, for example, bears involved in dog fights have claws and teeth pulled out. Of course, currently, dog fights are forbidden in most countries.