A striking and active schooling fish endemic to the high-altitude, fast-flowing mountain streams of Papua New Guinea. Because of their natural habitat, they are unique among Rainbowfish for requiring significantly cooler, highly oxygenated water. They feature a blue-grey to greenish body with a distinct black mid-lateral stripe and coppery golden scale margins.
Mountain Rainbowfish At a Glance
Mountain Rainbowfish Tank Requirements
Will Mountain Rainbowfish fit in your tank?
Care guides tell you what Mountain Rainbowfish needs, the next question is whether your tank can safely provide it. Test Mountain Rainbowfish against your tank size, maintenance needs, and the fish you already keep before you buy.
Useful setup supplies
We may earn from qualifying purchases
Mountain Rainbowfish Water Parameters
Water care products
We may earn from qualifying purchases
Mountain Rainbowfish Temperament & Compatibility
Mountain Rainbowfish Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
As they mature, males develop a significantly deeper body profile, elongated dorsal and anal fins, and more vibrant coloration, including a pale lilac hue on the breast. They will actively spar and display for females.
Differs in 2 traits from base species
Also known as: Male Monticola, Show Male
Female
Females are generally smaller, maintain a more slender and streamlined body profile throughout their lives, and feature translucent fins rather than the elongated, colorful fins of the males. A proper shoal should ideally have a ratio of more females than males to prevent harassment.
Differs in 2 traits from base species
Also known as: Female Monticola
Mountain Rainbowfish Care Guide Summary
The Mountain Rainbowfish, scientifically known as Melanotaenia monticola, 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 low level of biological waste.
To thrive, the Mountain Rainbowfish requires a freshwater only aquarium with a minimum volume of 110 litres and a tank length of at least 90 cm. Water temperature should be maintained between 17°C and 24°C, with a pH range of 7.4–8.5 and a general hardness of 8–20 dGH. A high water flow is preferred.
The Mountain Rainbowfish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: 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.
Mountain Rainbowfish Habitat Setup
When setting up an aquarium for the Mountain Rainbowfish, a high water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include driftwood, which can serve as both a hiding place and a dietary supplement. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Mountain Rainbowfish Compatibility Notes
Classified as peaceful, the Mountain Rainbowfish is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.
Mountain Rainbowfish Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Mountain Rainbowfish.
30 Gallon Breeder
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
Show 10 more tank sizes
Feeding products
We may earn from qualifying purchases
.webp?2026-04-25T14%3A35%3A38.022Z)
Frequently Asked Questions About Mountain Rainbowfish
How big does Mountain Rainbowfish get?
Mountain Rainbowfish (Melanotaenia monticola) typically reaches a maximum adult size of approximately 10 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Mountain Rainbowfish need?
A minimum aquarium volume of 110 litres and a tank length of at least 90 cm are recommended for Mountain Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Mountain Rainbowfish need?
Mountain Rainbowfish thrives in freshwater only conditions with a temperature range of 17–24°C, a pH between 7.4 and 8.5, and a general hardness of 8–20 dGH. A high water flow is preferred.
Is Mountain Rainbowfish peaceful or aggressive?
Mountain Rainbowfish is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.
How many Mountain Rainbowfish should be kept together?
Mountain Rainbowfish is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Mountain Rainbowfish have any special tank requirements?
Yes. Mountain Rainbowfish benefits from driftwood (digestion/hiding) in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Mountain Rainbowfish need a lid on the tank?
Yes. Mountain Rainbowfish is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Top Tank Mates for Mountain Rainbowfish
These fish are strong compatibility matches for Mountain Rainbowfish based on water preferences, temperament, adult size, and tank behavior.
Pacific Sturgeon
Acipenser transmontanus
Ideal Tank MatesHillstream Loach
Beaufortia leveretti
Ideal Tank MatesEmerald Green Cory
Corydoras splendens
Ideal Tank MatesAgassiz Cory
Corydoras agassizii
Ideal Tank MatesCommon Pleco (Amazon Sailfin)
Pterygoplichthys pardalis
Ideal Tank MatesDojo Loach (Weather Loach)
Misgurnus anguillicaudatus
Ideal Tank MatesPlants That Suit Mountain Rainbowfish
These plants pair well with Mountain Rainbowfish based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
African Water Fern
Bolbitis heudelotii
Boivin's Aponogeton
Aponogeton boivinianus
Madagascar Lace Plant
Aponogeton madagascariensis
African Onion Plant
Crinum calamistratum
Afzel's Anubias
Anubias afzelii
Amazon Sword
Echinodorus amazonicus
Fish Similar to Mountain Rainbowfish
Highlands Rainbowfish
Chilatherina campsi
A rare and elegant species endemic to the central highlands of Papua New Guinea. Unlike many tropical rainbowfish, it thrives in slightly cooler, well-oxygenated water. They are very active, peaceful schooling fish characterized by an olive/mauve back, silvery reflections, and a distinct blackish-to-blue mid-lateral stripe.
Bulolo Rainbowfish
Chilatherina bulolo
A rare and highly active rainbowfish native to the fast-flowing mountain streams and white-water rapids of the Markham and Ramu river systems in Papua New Guinea. They possess a silvery body with a distinct black streak on the upper and lower edges of the caudal fin. Because of their specialized natural habitat, they require highly oxygenated, fast-flowing water and alkaline conditions to thrive in an aquarium.
New Guinea Rainbowfish
Melanotaenia affinis
An active, schooling species native to the streams of northern New Guinea. Known for their striking lateral stripe and vibrant fin coloration that flashes during morning displays. They are peaceful but highly energetic, requiring ample open swimming space and highly oxygenated water to thrive.
Lake Tebera Rainbowfish
Melanotaenia herbertaxelrodi
A striking, highly active schooling fish endemic to Lake Tebera in Papua New Guinea. They feature bright yellow to greenish-blue bodies with a distinct dark lateral stripe. As vigorous swimmers, they require long aquariums and do best in mixed-sex shoals, which encourages males to display their best colors. Due to their highland origin, they prefer slightly cooler, well-oxygenated, and alkaline water.
Blue Rainbowfish
Melanotaenia caerulea
A small, highly active, and colorful schooling fish native to the Kikori River system in Papua New Guinea. They are peaceful but require ample swimming space and a school of their own kind to thrive. Like most rainbowfish, they appreciate well-oxygenated, flowing water and are excellent jumpers. Males develop a striking blue hue with reddish horizontal stripes.
Kamaka Rainbowfish
Melanotaenia kamaka
Endemic to the karst Lake Kamakawai in West Papua, this is a spectacular and distinctively deep-bodied rainbowfish. As they mature, males develop a robust chest and an intense silvery-blue to purplish sheen. Like all rainbowfish, they are highly active, schooling fish that require spacious tanks with plenty of horizontal swimming room and alkaline, hard water parameters.