Half Moon Male Betta (Betta splendens)

Halfmoon bettas are bred for one very specific number: a 180-degree tail spread with a straight top and bottom edge, so the fully flared caudal fin forms a perfect semicircle behind the body. American breeders locked that standard in during the 1980s, and it's been the benchmark show tail ever since. Getting the edges that straight takes generations of selective pairing, which is why a good one costs more than a pet-store special.

Care level: Easy · Temperament: Aggressive toward other bettas · Max size: ~3" · Min tank: 5 gal · Diet: Carnivore, betta pellets + frozen