Siamese fighting fish

The alien betta is not a single species but a line of hybrids built from members of the Betta splendens complex, crossing wild species such as B. smaragdina, B. mahachaiensis, and B. stiktos with domestic bettas. The result is a fish with heavy metallic iridescence, often a turquoise or copper body laced with a fine net of dark scale edges that gives a reptilian, alien look. These labyrinth fish trace back to the warm, still waters of Southeast Asia and, like all bettas, gulp air at the surface to supplement their gills.

Alien bettas keep the temperament of their wild ancestors: males are territorial and should be housed one to a tank, and they are quick, alert, and prone to jumping, so a tight lid matters. They are carnivores that relish live and frozen foods such as bloodworm, daphnia, and brine shrimp alongside a quality betta pellet. A single male can lead a peaceful community of small, calm fish, but avoid fin-nippers and other gouramis, and treat dwarf shrimp as potential snacks rather than reliable tankmates.

Keep alien bettas in a heated, gently filtered tank of at least 20 litres at 24 to 30 degrees Celsius, in soft to moderately hard water that is slightly acidic to neutral. Many keepers find these hybrids a touch hardier and more vigorous than long-finned show bettas. They breed like other bettas, with the male building a surface bubble nest, fertilising the eggs in an embrace, and guarding the fry alone. Because alien bettas are hybrids, their offspring do not breed true to type, which is why fixing their dramatic patterns is the work of specialist breeders.