Betta fish, commonly referred to as Siamese fighter fish, are one of the most popular fish breeds. With its jewel-toned colouring and flowing fins, betta fish are a great addition to any fish-lover's home. Not all betta fish fight—only the males. Female bettas can be kept together. Despite how they are often sold, bettas should not be kept in a fish bowl. Bettas are happiest when kept in water that is soft, warm, with a neutral to slightly acidic pH.