An incredibly popular and active schooling fish endemic to the Ajamaru Lakes in West Papua, Indonesia (currently listed as Endangered in the wild by the IUCN due to overfishing and habitat loss, though commercially captive-bred). Famous for the mature male's spectacular blue and orange split-coloration. They require long tanks for active swimming, excellent oxygenation, and warm, hard, alkaline water to thrive.
At a Glance
Tank Requirements
Water Parameters
Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Adult males develop a highly arched back (deep body) and the iconic two-tone coloration: a bluish-purple front half and a vibrant orange-yellow rear. They continuously display to females and spar harmlessly with rival males. Best kept in a ratio of 1 male to 2 females, or in large groups.
Differs in 1 trait from base species
Also known as: Show Male, Adult Male
Female
Females are slightly smaller, more streamlined, and have subdued coloration (mostly silver/grey with yellowish fins and faint horizontal stripes). Keeping a proper female-heavy ratio reduces harassment stress and brings out the males' most intense display colors.
Differs in 1 trait from base species
Also known as: Female
Unsexed Juvenile
Most commonly found in stores at 3-5cm. Juveniles of both sexes are relatively colorless and silvery. It takes several months of high-quality diet and pristine water conditions for males to develop their characteristic deep body shape and dramatic colors.
Differs in 1 trait from base species
Also known as: Baby, Juvenile
Boeseman's Rainbowfish Care Summary
The Boeseman's Rainbowfish, scientifically known as Melanotaenia boesemani, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 10 cm and have a compressed body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a medium level of biological waste.
To thrive, the Boeseman's Rainbowfish requires a freshwater only aquarium with a minimum volume of 200 litres and a tank length of at least 120 cm. Water temperature should be maintained between 26°C and 30°C, with a pH range of 7–8.1 and a general hardness of 9–19 dGH. A moderate water flow is preferred. To replicate their natural habitat, the tank should include plants - lighly covered.
As a schooling species, Boeseman's Rainbowfish should be kept in groups of at least 6. Keepers should be aware that this species is a known jumper, so a tight-fitting lid is essential. This species is available in 3 varieties: Male, Female, and Unsexed Juvenile. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Similar Species
Turquoise Rainbowfish
Melanotaenia lacustris
A stunning, deep-bodied rainbowfish endemic to Lake Kutubu in Papua New Guinea. Famous for their ability to shift colors from deep teal to bright iridescent blue depending on mood and water quality. They are active schooling fish that thrive in hard, alkaline water.
Red Rainbowfish
Glossolepis incisus
Native to Lake Sentani in Indonesia, this species is famous for the brilliant salmon-red coloration of mature males. They are large, active schooling fish that develop a distinct high-arched back as they age. Females are vastly different in appearance (olive-gold). They require hard, alkaline water and plenty of swimming space.
Dwarf Neon Rainbowfish (Praecox)
Melanotaenia praecox
A brilliant, active schooling fish native to the Mamberamo River basin in West Papua. Known for their iridescent neon-blue bodies, they are an energetic and peaceful addition to community tanks. Because of their high activity levels, they require ample open swimming space alongside planted areas. They are fast eaters and may outcompete shy tank mates for food.
Threadfin Rainbowfish
Iriatherina werneri
A delicate and exquisitely shaped nano rainbowfish native to New Guinea and Northern Australia. They are famous for the males' long, filamentous fins and butterfly-like display behavior. Due to their incredibly small throats, they require micro-foods. They are shoaling fish that are easily intimidated by boisterous tank mates.
Neon Tetra
Paracheirodon innesi
One of the most iconic freshwater fish in the hobby, famous for its striking iridescent blue and red stripes. Originally from the blackwater streams of the Amazon basin, they prefer slightly cooler water than many tropical fish and must be kept in schools to thrive, display natural behaviors, and feel secure.
Japanese Ricefish (Medaka)
Oryzias latipes
A hardy, small, and colorful fish native to East Asia. Extremely popular in the outdoor pond hobby and nano aquariums. They are 'amphidromous' (tolerant of salinity changes) and can survive a wide range of temperatures, making them excellent tub/pond fish. They are surface dwellers that look best when viewed from above (top-down).