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 ...

Bettas are one of the most popular fish species. Most people consider them relatively active, but this isn’t always true.

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.