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 ...

Betta, or Siamese fighting, fish are among "the most popular freshwater aquarium fish in the world," PetMD reports. Native to southeast Asia, this species is known for its range of vibrant hues.

and they should never share their tank with another betta fish. The males of the species will fight one another, and not all female betta fish get along with other betta fish. "All betta fish ...