Dwarf rainbowfish

Aquarium fish: Dwarf rainbowfish (Melanotaenia praecox)
Size: 6 cm
Origin: New Guinea
Water temperature: 23-28 ° C
Aquarium volume: 75 l

Dwarf rainbowfish (Melanotaenia praecox) – attractive, freshwater aquarium fish from the rainbow family.


New Guinea . Endemic, it inhabits smaller rivers and streams and the surrounding floodplain in Papua’s Mamberamo basin. Fish can be found near plant clusters and sunken roots and tree branches.

Characteristics and disposition

Beautiful and hardy fish.

In nature, they reach a length of 8 cm, in aquariums slightly less – 6 cm. The name of this species refers to the blue, opalescent color that can be admired in adult specimens kept under optimal conditions. Males are smaller, slender and brightly colored than females. Their torso is more silvery and the fins are more orange (more yellow in females). Like other rainbow fish, they can be skittish and therefore it is better to keep them in a group of at least 6-8 individuals, preferably 10 or more.

Shoal males show their best colors.

Nutrition and feeding

They are not picky fish and will eat most of the available dry, frozen and live food. Regular administration of the latter will have a beneficial effect on their coloration.


Dwarf rainbowfishs look best against the background of a densely planted reservoir with a dark substrate and not too brightly lit. Too bright light can be diffused by e.g.

floating plants. These fish also need open swimming areas and areas where males can compete with each other. For 10 or more fish, an aquarium of more than 100 liters will be required. Requires high-quality water – recommended weekly water changes (20%). A very gentle species and due to its small size it is suitable for a social aquarium.

Good company will be other, similarly sized rainbow, tetras, zebrafish , barbs, cichlids , cuirass and freshwater plantain.


Dwarf rainbowfish fish reproduction is not difficult , however, rearing fry, especially in the first stages, can be troublesome. The spawning tank should be at least 45 cm long. Medium hard water, slightly acidic to slightly alkaline, approx. 7.0 pH and temperature 24-27 ° C.

Place small-leaved plants in the aquarium, e.g. Java moss or an artificial aquarium mop. A substrate is not necessary. Before the planned reproduction, we feed adults generously with live and frozen food. When the females will be fuller around the abdomen and the males will take on more intense colors, we choose the thickest female and the most beautiful male and transfer them to the spawning tank.

Often times, a slight increase in temperature can encourage fish to spawn. The steam is rubbed over several days, scattering the spawn daily. The eggs stick to the surface with small threads. Parents tend to eat the eggs. It is recommended to regularly check the plants or mops and transfer the grains found to a separate aquarium or container (water must come from the breeding aquarium).

Depending on the temperature, it takes 7-10 days to hatch. The fry in the first week require micro-foods (protozoa, ciliates). After a week, they can be given artemia and shellfish larvae. The falling food will not be appropriate because the fry swim near the surface of the water.


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