The Boesemani Rainbowfish: Characteristics and Care

The colors of this rainbowfish can reflect the health of the animal. If they're in poor condition, their tones become duller. When the water parameters are stable, it begins its reproductive period.
The Boesemani Rainbowfish: Characteristics and Care
Cesar Paul Gonzalez Gonzalez

Written and verified by the biologist Cesar Paul Gonzalez Gonzalez.

Last update: 21 December, 2022

The Boesemani rainbowfish is one of the most attractive and beloved aquarium species. In addition, they’re active and peaceful specimens, so they combine well with other similar fish. Although it isn’t difficult to look after them, the water quality must be monitored, which constitutes the greatest complexity of their requirements.

There are several types of rainbowfish, but they all belong to the Melanotaeniidae family. For this reason, in this space, we’re going to talk specifically about Melanotaenia boesemani, the most colorful specimen within this group. Read on to learn more about this organism that will fill your aquarium with life and color.

Boesemani rainbowfish characteristics

The shape of the body of this fish is oval and flattened, with very poorly developed fins and small overall sizes, barely 10 centimeters (4 inches) long. In addition, only the dorsal and anal fins stand out, as they look like veils or margins with colors on their edges, which finely adorn the vertebrate.

The colors of this species are one of its remarkable qualities, as they fully honor its name. The body shows blue, turquoise or violet flashes in the first half, and then yellow, orange and some red appear.

Rainbowfish are considered to be the most colorful of the entire Melanotaeniidae family.

Sexual dimorphism

Although all the specimens usually have the same colors, the females have duller tones than the males. This difference serves as sexual dimorphism, as the male uses his appearance to attract the female during the mating season. In fact, there are also slight differences in the appearance of the body, since the females turn out to have a finer and more stylized shape.

Natural habitat

This rainbow fish is native to Lake Ajamaru and Aitinjo (in West Papua), although there are other species of its family that inhabit northern Australia and part of New Guinea. Due to their great adaptability, it’s feared that these organisms could invade other ecosystems anywhere in the world.

The natural habitat of these fish is made up of crystalline fresh waters, with a lot of vegetation and an approximate pH of 8.0. In addition, they occupy shallow areas with a maximum of 10 meters depth (32 feet), with temperatures between 25 and 28 degrees Celsius, something quite normal in tropical waters.

A rainbow fish in an aquarium

Boesemani rainbowfish care

To be in good health in captivity, this rainbowfish must have a tank of at least 200 liters. Likewise, it must also be provided with a good amount of vegetation, as it usually uses it as a hiding place and allows it to relax.

Remember that one of the most complicated processes for your fish will be to adapt to its new home. Providing them with rocks or hiding places will help them stay calm.

Because it’s a gregarious fish, we recommend that they share a tank with between 6 and 8 more individuals. In addition, it’s usually a good companion for peaceful species, which is why it can be added to community tanks. Before deciding, keep in mind that Boesemani rainbowfish live in slightly alkaline waters. Because of this, you need to make sure that the others support these requirements.

Water parameters

Although their care is simple, these fish need very special conditions in the water, which is considered the most difficult part of their care. For this reason, the following parameters must be taken with extreme caution and try to be fully maintained:

  • Temperature: 26 to 28 ° C.
  • pH: 6-8 (optimal range 7-8).
  • Hardness: 10-20 ° H.
  • Water replacements: Minimum 25% weekly. This species requires a filter in the tank.

Care prior to the arrival of the fish

If it’s the first time that you’ve had a working aquarium, you need to carry out the maturation of the tank. Install all your equipment and put it to work so that the environment stabilizes and creates a functional mini-ecosystem. To advance the process, a little food is usually put in the tank and left cycling for a few weeks.

The stabilization of the aquarium parameters usually takes a month.

Before you introduce your fish to the aquarium, it’s necessary to acclimatize it so that it doesn’t overstress. To do this, the bag or container it came in should be placed into the tank, so that the temperature begins to equalize. After this, the water in the container begins to mix with that of the aquarium, slowly and continuously, to achieve homogenization of both media.

These processes are tedious and require patience, but they’ll help your new pet adapt better to its new home and enjoy a good life. Remember that one of the factors that affects fish health is stress: the more you take care of these points, the better their immune system will respond.

Boesemani rainbowfish diet

In its natural state, this fish is an omnivorous creature, which is why it eats a wide variety of types of food. For this reason, in captivity, it won’t give you any problems in this regard, as it can be maintained on the basis of any type of processed flakes (pellets) or live food. In fact, the shape of its mouth has a slight upward curve, allowing it to easily feed on the surface.

Due to the variety of commercial foods, and as there isn’t one that contains everything you need for your fish’s nutrition, it’s best to offer both types of food – live and processed. Likewise, it can be a demanding pet, as you will have to feed it between 2 and 3 times a day.

Reproduction of the rainbow fish

The reproduction of this species is simple, since it doesn’t require additional specific care. What’s more, most of the specimens that are sold come from specialized farms. Due to their success and relatively low maintenance cost, they have become popular fish with aquarists.

Mating ritual

The male makes his courtship by means of a “dance”, trying to attract the female. At this moment, a swim begins that alternates movements from left to right, quite slow and very similar to a waltz. Finally, the male attacks the female 4 to 9 times, and if she accepts, spawning and fertilization begin.

Egg laying and hatching

To begin with, these fish are oviparous, so they stick their eggs directly on the leaves of the vegetation, where they wait for them to be fertilized. Being specimens with external fertilization, it’s the male who finishes the process, depositing his sperm on them.

These organisms lay between 19 and 56 eggs at a time. Although they can spawn at any time, they have a preference for the early hours of the day. In fact, there’s no specific mating period for this species, so it can happen at any time of the year, as long as they have the right food and conditions.

The eggs will hatch between 5 and 14 days after laying, depending on the temperature of the water. At warmer temperatures, the hatchlings will hatch earlier, while at colder temperatures their hatching is delayed. Like an adult, the feeding of the offspring has to be balanced, between processed and live food.

Final recommendations

If you want to live the experience of reproducing your specimens, it’s recommended that you do so with the advice of an expert. Although it may seem simple, the young require simple and continuous care that could cost them their lives if they’re neglected. One of the best strategies is to keep them in a different pond, so that they’re cared for specifically, without affecting the adults.

The Bosesemani rainbowfish is considered a threatened species, because its natural population has decreased alarmingly. However, these fish have proven to be easy to reproduce in captivity, so their survival in artificial environments is assured.

This isn’t the best way to save a species, but it’s better than it facing extinction.

A rainbow fish in an aquarium

In addition, you must be aware of your responsibility with this pet, as it will depend on you throughout its life. However, if you follow all the recommendations and get advice from experts, you won’t have any problems looking after them, and you’ll enjoy one of the most beautiful specimens that exist.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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  • Nugraha, M. F. I., Pouyaud, L., Carman, O., Widyastuti, U., Junior, M. Z., Kadarusman, & Avarre, J. C. (2015). Genetic diversity of Boeseman’s Rainbowfish (Melanotaenia boesemani) reared in Indonesian farms compared to endangered natural populations. Tropical Conservation Science8(3), 796-812.
  • Hismayasari, I. B., Marhendra, A. P. W., Rahayu, S., Saidin, S. D., & Supriyadi, D. S. (2015). Gonadosomatic index (GSI), hepatosomatic index (HSI) and proportion of oocytes stadia as an indicator of rainbowfish Melanotaenia boesemani spawning season. International Journal of Fisheries and Aquatic Studies2(5), 359-362.
  • Radael, M. C., Fosse, P. J., Silva, R. M. D., Fosse Filho, J. C., Andrade, D. R. D., & Vidal Junior, M. V. (2016). Morphological description of Melanotaenia boesemani ovaries in reproductive activity. Pesquisa Veterinária Brasileira36(9), 893-900.
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  • Radael, M. C., Cardoso, L. D., de Andrade, D. R., Ferreira, A. V., da Cruz Mattos, D., & Vidal, M. V. (2016). Effect of temperature on embryonic development of Melanotaenia boesemani (Allen and Cross, 1982). Zygote24(2), 301-309.
  • Allen, G. R., & Cross, N. J. (1980). Descriptions of five new rainbowfishes (Melanotaeniidae) from New Guinea. Records of the Western Australian Museum8(3), 377-396.
  • Martínez-Castro, A., & Ramírez-Herrera, M. (2016). Catálogo de peces ornamentales producidos en Morelos con capacidad de ser especies exóticas invasoras (EEI) elaborado dentro del proyecto GEF 00089333 “Aumentar las capacidades de México para manejar especies exóticas invasoras través de la implementación de la Estrategia Nacional de especies Invasoras”. Morelos, México.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.