Dwarf rainbowfish

The dwarf rainbowfish (Melanotaenia praecox), also called the neon dwarf rainbowfish, is a small, brilliantly coloured species endemic to the Mamberamo River system in Papua, Indonesia. Males reach about 8 cm (3.2 in) and develop an iridescent neon blue body with bright red-orange fins and a deep, compressed body profile, while females remain smaller, silverer, and less intensely coloured. They are active midwater swimmers that bring constant motion and colour to a planted community tank.

Despite their small size, these fish need generous swimming space: a tank of at least 60 x 30 cm (55 L / 15 gal) is recommended, furnished with dense planting along the sides and open swimming areas in the centre. Floating plants help diffuse lighting, which encourages the fish to stay active and display their best colours. High water quality is essential, with weekly partial water changes. Temperature should be 23-28C (73-82F), pH 6.8-7.5, with moderate hardness of 5-15 dH. They are unfussy omnivores and accept most dried, frozen, and live foods.

Dwarf rainbowfish are very peaceful but can be skittish, so they must be kept in groups of at least six to eight, ideally more. Males display constantly to one another, which encourages the best colouration without serious aggression. Suitable tankmates include other small rainbowfish, characins, danios, barbs, dwarf cichlids, and Corydoras catfish. Breeding is straightforward: the pair scatter eggs among fine-leaved plants or spawning mops over several weeks, with the eggs hatching in 7-8 days. With good care they can live 4-5 years.