Neon Dwarf Rainbowfish (Melanotaenia Praecox)

Description & Origin


Melanotaenia praecox was scientifically described by Weber and Beaufort in 1922 but first introduced in 1992. This species is endemic to the Mamberamo river system in the island of New Guinea, in the Indonesian province of Papua. This is considered one of the largest river systems on the island, being over 2,000 km long. Dwarf rainbowfish belongs to kingdom Animalia, phylum Chordate, and class Actinopterugii. There is no sufficient data available to describe their population status, but the dwarf rainbow fish last listed in 1994 as a rare species.

Dwarf rainbowfish is not difficult to maintain once it settles in the aquarium environment. It is a peaceful and non-aggressive species. Therefore, peaceful aquarium species of similar size are recommended as tankmates for this fish such as characins, danios, barbs, dwarf cichlids, freshwater gobies, and Corydoras.

This lovely small rainbowfish has most of the characteristics of the rainbowfish family, except for its relatively miniature size. This fish can only reach up to 5 – 7 cm (2 – 2.5 inches) in length. It has a long body that deepens with age. Melanotaenia praecox has big eyes and twin dorsal fins like its larger cousins.


Dwarf Neon Rainbow Fish has a few unique characteristics including the brightly colored fins that are red on males and yellow on females. The body color is pinkish and gray, but the scales will light up in bright blue by reflecting the light. Depending on the light, the tints of blue are surprisingly varying from lavender to teal (a medium blue color).

It usually has a lifespan of about 3-5 years. This little rainbowfish is ideally suited to a heavily planted tank setup and will show its best colors in such surroundings. It doesn’t like bright lighting and using some floating plants such as water lettuce or water hyacinth to diffuse the light would be the best for its comfort. Allowing open spaces between the planted areas to provide swimming space will be a proper design to provide the fish with some social areas. Good water quality is essential for the well-being of this species, thus weekly partial water change to increase water quality and removal of hazardous wastes is ideal.

Water parameters:

Temperature: 23-28°C
pH: 6,8 – 7,5
Hardness: 5-15 dGH


Dwarf Neon Rainbowfish is an omnivore and quite equally adapted to eating both animal and vegetative foods. In captivity, Melanotaenia praecox will accept high-quality flake or pellet foods. It is better to buy foods frequently in small amounts, as the nutritional value of these products quickly deteriorates in time. Another large chunk of their diet should be live foods like brine shrimp, bloodworms, and tubifex worms. Dwarf Neon Rainbowfish also enjoy vegetables such as lettuce and spinach leaves.



As with other members of the rainbowfish genus, Melanotaenia praecox is not a difficult fish to breed. However, surviving the tiny fry is somewhat tricky in the early stages.

The adult fish conditioned as a group in a separate aquarium with plenty of live and frozen foods are proper for breeding. As the fish come into condition, the females will appear noticeably plump while watched from the sides.

A small temperature rise will induce spawning (2-3 °C). The breeding group will spawn for several weeks by laying batches of eggs every day. The eggs will be attached to surfaces with small threads of the floating plant roots or other aquatic plants.

The adults eat the eggs and fry after spawning. It’s easier to raise the fry alone in a separate aquarium. So, after spawning the breeding adults must be removed. Another option is checking the plants regularly and remove the ones with eggs to a dedicated tank or using spawning mops and remove any eggs found to a separate raising tank. The important thing in doing this is providing the same water conditions in the raising tank or moving some part of the spawning tank together with the eggs.

The eggs will hatch in approximately 7-10 days, depending on the water temperature. Sinking foods are unsuitable for feeding the fry as they tend to stay very close to the water surface. It is better to feed the fry with powder foods in small amounts in the first few days. FD rotifer or FD cyclops is also an alternative for the first stage. It is better to keep the water level low to easily observe the fry and enable them to reach any sunken food. Also, artemia nauplii and micro worms are good sources of food for the fry.

Image Source:

0 0 votes
Rate This Page
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments