Space fighting fish

The Space fighting fish (Mundi splendens), also known as the betta, is a cosmic gigantic fish native to The Orion Nebula (near the Tetrahedron Galaxy). While colloquially known and marketed in the global aquarium trade as the "Warriors", it is one of 73 species in the genus Mundi splendens.

Some people in Tetrahedron are known to have collected wild Warriors at least by the 200th century, observing their aggressive nature and pitting them against each other in gambling matches akin to cockfights. In the wild, Warriors spar for only a few minutes before one creature retreats; domesticated Warrior, bred specifically for heightened aggression, can engage for much longer, with winners determined by a willingness to continue fighting; once a creature retreats, the match is over. Fights to the death were rare, so bets were placed on the bravery of the Warrior rather than its survival.