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.
At a Glance
Tank Requirements
Water Parameters
Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard / Mixed Sex
Commonly sold as juveniles (4-6cm). Coloration may be muted silver/grey until maturity. Must be kept in schools of 6+ to reduce stress.
Differs in 2 traits from base species
Also known as: Juvenile
Male
Mature males develop a very deep chest (nuchal hump) and intense turquoise coloration. They display frequently to females and rival males.
Differs in 3 traits from base species
Also known as: Show Male
Female
More slender and often slightly smaller than males. Color is a more muted bluish-silver. Essential in the school to encourage male coloration.
Differs in 1 trait from base species
Turquoise Rainbowfish Care Summary
The Turquoise Rainbowfish, scientifically known as Melanotaenia lacustris, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 12 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 Turquoise Rainbowfish requires a freshwater only aquarium with a minimum volume of 160 litres and a tank length of at least 120 cm. Water temperature should be maintained between 20°C and 25°C, with a pH range of 7–9 and a general hardness of 10–25 dGH. A moderate water flow is preferred. To replicate their natural habitat, the tank should include plants - densely covered and plants - lighly covered.
As a schooling species, Turquoise 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: Standard / Mixed Sex, Male, and Female. 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
Boeseman's Rainbowfish
Melanotaenia boesemani
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.
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.
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.
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.
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.
Peacock Gudgeon
Tateurndina ocellicauda
A stunning, peaceful freshwater sleeper goby from Papua New Guinea. Known for their vibrant blue, red, and yellow colors, they are excellent nano-tank inhabitants. They are not true gobies (they lack fused pelvic fins) and are exclusively freshwater. They prefer slow-moving water, dense vegetation, and small caves (like PVC pipes or smooth stones) for spawning.