What is a betta fish? Betta fish—also known as Siamese fighting fish—are among the oldest species of domesticated fish. Their scientific name, Betta splendens, combines two languages ...

Photo: T.X. Betta fish are famous for their strikingly colorful fins ... "When bettas get agitated or prepare for battle, their fins flare wide, and their colors become even more vivid and dazzling," ...