Red Rainbowfish Male

Glossolepis incisus is one of the most spectacularly coloured freshwater fish in the world. Adult males develop a uniformly deep blood-red to crimson body with a strongly arched, hump-backed profile, vivid orange-red fins, and a large, impressive overall size reaching up to 15 cm. The transformation from the silver-olive juvenile to the fully scarlet adult male takes 12–18 months and is one of the hobby's most dramatic colour progressions.

Females and juveniles are far more subdued — silvery-olive with yellow-tinged fins — and the striking sexual dimorphism means single-sex male groups or mixed groups produce very different visual impacts. This species originates from Lake Sentani and surrounding waters in West Papua, where it lives in warm, moderately hard, slightly alkaline water. It is well-established in the hobby and available from specialist breeders.

Glossolepi incisus requires a spacious aquarium — at least 250 litres for a small group of males — with excellent filtration and weekly large water changes. It is not demanding with regard to feeding and eagerly accepts a wide range of foods. Males can be slightly intimidating to very small tankmates but are fundamentally peaceful with fish of comparable size.

Water: pH 7.0–8.0, temperature 22–27°C, moderately hard; pristine water quality maintains colour saturation. Tank: Minimum 250 L for adults; open swimming space; avoid overcrowding to minimise stress-induced fading. Feeding: Accepts all quality flake, pellets, and live or frozen foods; varied diet supports full colour development. Breeding: Egg scatterer; condition on live foods; 1 male to 2–3 females reduces female stress. Compatibility: Peaceful with medium-to-large fish; stunning centrepiece in a large community or rainbowfish-only tank.