Boeseman’s rainbowfish Care, Lifespan, Feeding, Algae Eating, Size..

When the first specimens of Boeseman’s rainbowfish went on sale in 1983, they caused a sensation. Until then, fish from New Guinea had hardly been imported, and then such colour wonders. Today Boeseman’s rainbowfish swims in many aquariums and has not lost any of its attractiveness.

Boeseman's rainbowfish


Name: Boese Mans Rainbow Fish, Melanotaenia boesemani

system: Rainbow Fish

size : 10-12 cm

origin: Bird’s Head Peninsula, West Papua, New Guinea

attitude: simply

Aquarium size: 300 litres (150 cm edge length)

pH: 7-8

water temperature: 22- 25 ° C

Interesting facts about Boeseman’s rainbowfish

Scientific name

Melanotaenia boesemani

Other names



Class: Actinopterygii (ray fins)

Order: Atheriniformes (ear fish-like)

Family: Melanotaeniidae (rainbowfish )

Genus: Melanotaenia

Species: Melanotaenia boesemani (Boesemans rainbow fish )


These rainbow fish reach a length of about 10 cm in the aquarium. In large aquariums from 400 l, however, it can also be 12 cm or even more.


The males are metallic light bluish in front in normal colour, through the middle runs a weak, vertical, dark stripe and the rear body is orange. The females look like a paler image of the males, during courtship (morning and evening, especially glorious in the morning sun), the colours of the male change. The front part of the body turns steel blue to almost black, the central stripe black and the rear part bright orange. With some colour variants, the rear part of the courtship can also be yellow or bright red.


Boeseman’s rainbowfish comes from the Ajamaruseen in the centre of the Vogelkopf Peninsula in western New Guinea (West Papua) and some adjacent rivers and lakes.

Gender differences

On the one hand, the sexes can be recognized by the stronger colouration of the males, which already appear at a length of 3 cm. They also have longer, more pointed dorsal and anal fins that reach the caudal fin’s base. In the case of females, they end well before that. During courtship, a golden-yellow to bluish courtship strip appears on the back of the male (snout to dorsal-fin base), which it can switch on and off in a fraction of a second.

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Rainbowfish – also this species – are permanent spawners. This means that the females lay some very small eggs every day, which are then directly fertilized by the male. They are adhesive and hang on the plants or an extra spawning mop in a separate spawning aquarium. They are very hard and can also be read and placed in a separate small aquarium. After about a week, the very small cubs hatch and immediately need food such as small infusoria or microalgae (Chlorella, Spirulina) but are then easy to raise.

Life expectancy

Boeseman’s rainbowfish can live to be over ten years old.

Interesting facts about posture


These rainbow fish are omnivores and will not take too much food. Since they can always find food in the aquarium (algae, also duckweed), they should be given one to two fasting days per week. Young fish, however, have to be fed more often (initially several times, up to about 5 cm in length twice a day).

Boeseman's rainbowfish

Group size

Rainbowfish like Boeseman’s rainbowfish only feel at home in a group. Since males can drive quite strongly, there should always be one to three more females than males. However, it is also possible to keep a squad that only consists of males, as the arguments are always peaceful.

Aquarium size

An aquarium from 300 l is sufficient for a small group of up to ten animals (corresponding to an edge length of 1.50 m). The larger the aquarium, the larger Boeseman’s rainbowfish can become and in very large aquariums (from 600 l) 15 cm have already been reached.

Pool equipment

Part of the aquarium should be densely planted so that the females can retreat there if the males chase them too hard. Stones and Wood are not necessary, but stones do not interfere. On the other hand, Wood could lower the pH value due to the tannins it contains, which would usually be unfavourable for keeping this fish. The substrate can be any, as Boeseman’s rainbowfish never visits the bottom.


Socialize Boeseman’s rainbowfish

Provided that the tank is large enough, Boeseman’s rainbowfish can be kept with all other peaceful fish. However, they should not be bigger than him. Otherwise, he could become shy, withdraw and not show the most beautiful colours. Since it lives in the middle layers of water, fish are particularly suitable for the substrate and those that live near the surface.

Required water values

The temperature should be between 22 and 25 ° C, the pH value between 7.0 and 8.0.


The appropriate diet for the rainbow fish in the aquarium consists of a mixture of live, dry and frozen food. This combination is supposed to cover all the nutrients you need. In nature, the rainbow fish feeds on approach food as well as growth. The latter is the algae lawn and the microorganisms that live in it. The rainbow fish has a small mouth so that it cannot eat larger chunks. Therefore, attention should be paid to the size of the food when feeding in the aquarium.

When feeding dry food, you should also pay attention to shelf life. If the container has already been open for six weeks, the feed must be disposed of. Because after this time, nutrients such as vitamins and unsaturated fatty acids spoil. In addition, mould could develop, which could harm the freshwater fish.


The juveniles of the rainbow fish often appear colourless in stores. They only develop their colours over time and shine brightly after a while. Another peculiarity is that males like to fight harmless fights. They are even more colourful than usual. In general, the rainbow fish is a peaceful ornamental fish that is well suited for community aquariums. But the different rainbowfish species should not be combined. Because they like to multiply with one another and undesirable crossings arise. Since the individual species are threatened with extinction, they should only be bred for each species.

Boeseman's rainbowfish

Information about individual rainbowfish species

Boeseman’s rainbowfish (Melanotaenia boesemani)

  • The keeping conditions for Boeseman’s rainbowfish
  • Melanotaenia boesemani have very sensitive mouths
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Diamond rainbowfish (Melanotaenia praecox)

  • Datasheet on diamond rainbow fish
  • The keeping conditions for diamond rainbow fish
  • Food for diamond rainbow fish
  • Advice on breeding

Filigree rainbow fish ( Iratherina werneri)

  • The keeping conditions for Iratherina werneri
  • Food for filigree rainbow fish
  • Problems buying filigree rainbow fish
  • The gender differences
  • Advice on breeding

Salmon red rainbowfish (Glossolepis incisus)

  • The sex differences in salmon rainbow fish
  • Advice on breeding

Buy Boeseman’s rainbowfish

Boeseman’s rainbowfish are to a limited extent readily available in local aquarium stores. A few providers also offer online purchases with professional shipping.