Betta fish are among the most popular aquarium fish worldwide but are among the worst-treated. The sale of individual bettas in tiny cups is a welfare practice that has attracted significant criticism.
Betta welfare failures operate at every scale: individual cup sale conditions cause chronic stress from minimal space, poor water quality, and lack of environmental complexity. Home tanks that are too small, too cold, or unfiltered repeat the same welfare problems. Fighting bettas — bred and trained for aggression — suffer traumatic injuries in staged combat. Their cognitive sophistication, including demonstrated learning and play-like behaviours, makes these welfare failures more serious than the trivial treatment bettas often receive would suggest.