Black Swordtail Male

The Black Swordtail is a melanistic captive variety of Xiphophorus hellerii in which selective breeding has pushed pigmentation toward a uniformly jet-black body and fins. Quality specimens show no patchy or partial pigmentation — the entire fish from snout to the tip of the sword is deep black with only subtle iridescent scaling visible at certain light angles.

The black colouration makes this a bold and graphic fish that creates strong visual contrast in community aquariums, particularly effective against brightly coloured tankmates or lush green planting. Males retain the energetic and assertive temperament of all swordtails.

Maintaining true black colouration requires careful selective breeding, as crosses with other swordtail colours tend to dilute the melanistic expression in offspring.

Water: 20–26 °C, pH 7.0–8.0, moderate to hard water. Tank: 100 L minimum; light or white substrate maximises the contrast of the black body. Feeding: Varied omnivore diet; protein-rich foods maintain the deep black colouration. Breeding: Breed true black to true black; crosses with other varieties dilute black colouration. Compatibility: Peaceful toward other species; one male per group.