Melanotaenia Boesemani


Melanotaenia Boesemani are a stunning member of the rainbowfish family. Unlike many of their Melantoneia brethren this fish does not feature prominent stripes, but will have half and half coloring when mature. They sport a dark blue-gray anterior, contrasted by bright orange fins and posterior. They show sexual dimorphism both in color patterns and size. Females sport duller colors. When mature they can have a paled version of the separately colored anterior and posterior as the males, but more commonly have a dark mid lateral stripe with series of narrow yellow or reddish-orange longitudinal stripes on the sides. They are a peaceful schooling fish suitable for community aquariums.

I feel that I should also note here that many of the fish shop specimens that you can purchase have what I call a “captive” flavoring to their color. Whether it is something lacking in the water or simple genetics and the way the farms cull the fry, but the anterior is often white or light colored, even as the fish ages, and the posterior portion is more commonly yellow than orange. When this fish is purchased from a source that has stock from the strains that were originally harvested and did not come from fish farms, the colors are much closer to the wild coloration described in the first paragraph. You can see the captive and immature coloring in the pictures accompanying this article.

Quick stats:

Listed tank sizes are the minimum
Size: Males 3.5 inches: females 2.8 inches | 9-7 centimeters
Tank: 31.5 inches | 80 centimeters
Strata: All
PH: PH recommendation 7.0 – 8.0
Hardness: dH range: 9 – 19
Temperature: 75°;F to 82°;F (24°;-28°; C)


Order: Atheriniformes (silversides)
Class: Actinopterygii
Family: Melanotaeniidae (Rainbowfishes, blue eyes)
Genera: Melanotaenia
Species: boesemani


Common name:

Boesemani Rainbowfish 

    , Boeseman’s Rainbowfish


Asia, Indonesia: 

    Inhabits lakes which are situated at the headwaters of the Ajamaru River in Irian Jaya which drains into the Kais River eventually flowing to the Ceram Sea.

General Body Form:As with the other Melanotaenia species, the body is rounder, and the fins and tail are not remarkable in size or shape. Males are fuller bodied and rounder than females.

Coloration:Males are colored brilliantly half and half. The head and anterior of the fish is dark blue gray with the posterior half and fins being reddish orange. In captive aquaria these colors are often “watered” down for reasons I postulated upon in the opening description.

Maintenance:This is a peaceful schooling fish. They should be kept in schools of 5 or more. And should have a ratio of 2 or more females per male if possible. Rainbowfish in general need nice clean water, M. boesemani is no exception. Provide them with a well filtered tank with good current and aeration and they will thrive. When water conditions are sub-optimal this fish is prone to developing columnaris, and a condition of columnaris that we call “threading.” You will see wisps of what looks like string or hair hanging off of the mouth or sides of the fish. This is a sure sign that the water conditions are sub-optimal and performing extra water changes will clear it right up.

Diet:They need an omnivorous diet. They love live insects, live blackworms, artemia, frozen foods, and flakes. But they should be provided with a good source of vegetation, as well. They will readily nibble on hair algae in the tank and duckweed, if made available to them.

These fish have ENORMOUS appetites. Anyone who has had them will know exactly what I am talking about. Their eyes are bigger than their stomachs, or mouths, I should say. Almost every boesemani owner has at one time or another had the pleasure of seeing one of their boes swimming around with a piece of an algae wafer way too big for their mouths stuck in there.

This is quite humorous and harmless most of the time since the wafer will dissolve. But there are times where a boesemani will try to eat a fish that is really too big and you will need to take immediate action in removing it, otherwise, you will lose both fish. You may want to pick tankmates wisely, with nothing too small. A fish an inch in size is too small to be in with a full grown boesemani. You may also want to feed any bottom feeders wafers that are way too big and you know the boes can’t get it into it’s mouth or break the wafer up small enough that you know it will dissolve and break up in the boes mouth should he try to eat it.

Biotope:M. boesemani is found in lakes in relatively clear shallow water, with abundant vegetation. The lakes and streams in its natural habitat are alkaline with PH in excess of 8.0.

Breeding:M.boesemani are open water/substratum egg scatterers. They do not guard their eggs, and normally will not eat their own fry. But give the fry plenty of hiding places if you decide to try to raise the with the adults just in case. Spawning females produce 100 – 200 eggs which adhere to water plants and hatch within 6 – 7 days.

Diseases:M. boesemani is prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial diseases

Boeseman’s rainbowfish from
Rainbowfish, A Complete Pet Owner’s Manual by Gunther Schmida
Baensch Aquarium Atlas 2, Third English Edition 1998

This profile was written by Mary an active contributor to the site.


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