Super Delta Betta (Betta splendens)

Tail spread in bettas isn't a binary trait, it's a continuous one, and "super delta" describes the zone just under the 180-degree halfmoon threshold, anywhere from about 160 to 179 degrees on a full flare. Getting that close without quite crossing into halfmoon territory still takes generations of selective pairing, and his labyrinth organ, which lets him breathe surface air, is put to good use in an unheated, uncirculated tank that mimics how the species actually lives. Solo housing only, his instinct to treat any other male's finnage as a threat doesn't dim just because he's a step below halfmoon grade.

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