Double Tail Betta
Betta splendens
About this strain
The Double Tail carries a genetic mutation that splits the caudal fin into two distinct lobes, giving the fish an almost symmetrical, butterfly-like profile from behind. The same mutation typically produces a broader, deeper body and a wider dorsal fin — often the widest of any betta type. This body shape is a double-edged sword: the expanded dorsal is gorgeous, but the short, wide body makes Double Tails prone to swim bladder issues and constipation. Feed sparingly, vary the diet, and avoid overfeeding. The Double Tail gene is also commonly used in breeding programs to widen finnage in other varieties.
Origin
The Double Tail mutation has appeared sporadically in Betta splendens for decades and is well-documented in Thai and U.S. breeding records from at least the 1970s. It's a naturally occurring gene rather than a single breeder's development.