The Lake Eacham Rainbowfish is a rare, highly active shoaling fish from Australia. It is famous in conservation circles for having been extirpated in its namesake crater lake, though it survives in surrounding watersheds and the aquarium hobby. They are peaceful but voracious surface feeders that require pristine water, moderate flow, and ample horizontal swimming space to thrive.
Lake Eacham Rainbowfish At a Glance
Lake Eacham Rainbowfish Tank Requirements
Will Lake Eacham Rainbowfish fit in your tank?
Care guides tell you what Lake Eacham Rainbowfish needs, the next question is whether your tank can safely provide it. Test Lake Eacham 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
Lake Eacham Rainbowfish Water Parameters
Water care products
We may earn from qualifying purchases
Lake Eacham Rainbowfish Temperament & Compatibility
Lake Eacham Rainbowfish Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male (Standard)
Males are slightly larger, develop a significantly deeper, arched body profile with age, and exhibit brighter, more intense coloration than females. They frequently display to establish dominance and court females within the shoal.
Differs in 2 traits from base species
Also known as: Show Male, Adult Male
Female / Juvenile
Females and juveniles retain a more slender, streamlined fusiform profile and subdued, silvery-yellow coloration. A proper shoal should contain a healthy mix of males and females (ideally a 1:1 or 1:2 ratio) to diffuse male displaying behaviors.
Differs in 2 traits from base species
Also known as: Unsexed
Lake Eacham Rainbowfish Care Guide Summary
The Lake Eacham Rainbowfish, scientifically known as Melanotaenia eachamensis, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 7.5 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 Lake Eacham 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 23°C and 27°C, with a pH range of 6.8–7.6 and a general hardness of 5–15 dGH. A moderate water flow is preferred.
The Lake Eacham Rainbowfish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: Male (Standard) and Female / 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.
Lake Eacham Rainbowfish Habitat Setup
When setting up an aquarium for the Lake Eacham Rainbowfish, a moderate 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 light plant coverage for partial shade. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Lake Eacham Rainbowfish Compatibility Notes
Classified as peaceful, the Lake Eacham 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, shy or slow-feeding tankmates may be outcompeted at feeding time and 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.
Lake Eacham Rainbowfish Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Lake Eacham Rainbowfish.
30 Gallon Breeder
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
Show 10 more tank sizes
Lake Eacham Rainbowfish Feeding & Diet Considerations
The Lake Eacham Rainbowfish will eat fry, so breeding efforts in the same tank are unlikely to succeed and is an aggressive eater that may prevent timid tankmates from getting enough food, so target feeding or simultaneous feeding at opposite ends of the tank can help.
Feeding products
We may earn from qualifying purchases
.webp?2026-04-25T14%3A35%3A38.022Z)
Frequently Asked Questions About Lake Eacham Rainbowfish
How big does Lake Eacham Rainbowfish get?
Lake Eacham Rainbowfish (Melanotaenia eachamensis) typically reaches a maximum adult size of approximately 7.5 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Lake Eacham Rainbowfish need?
A minimum aquarium volume of 110 litres and a tank length of at least 90 cm are recommended for Lake Eacham Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Lake Eacham Rainbowfish need?
Lake Eacham Rainbowfish thrives in freshwater only conditions with a temperature range of 23–27°C, a pH between 6.8 and 7.6, and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Is Lake Eacham Rainbowfish peaceful or aggressive?
Lake Eacham 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 Lake Eacham Rainbowfish should be kept together?
Lake Eacham 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 Lake Eacham Rainbowfish have any special tank requirements?
Yes. Lake Eacham Rainbowfish benefits from plants - lighly covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Lake Eacham Rainbowfish need a lid on the tank?
Yes. Lake Eacham 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 Lake Eacham Rainbowfish
These fish are strong compatibility matches for Lake Eacham Rainbowfish based on water preferences, temperament, adult size, and tank behavior.
Mottled Loach
Paracanthocobitis botia
Ideal Tank MatesSchwartz's Cory
Corydoras schwartzi
Ideal Tank MatesLeopard Cory
Corydoras leopardus
Ideal Tank MatesGold Laser Cory
Corydoras sp. 'CW010'
Ideal Tank MatesDainty Cory (Salt and Pepper Cory)
Corydoras habrosus
Ideal Tank MatesZebra Shovelnose (Tigrinus Catfish)
Brachyplatystoma tigrinum
Ideal Tank MatesPlants That Suit Lake Eacham Rainbowfish
These plants pair well with Lake Eacham Rainbowfish based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
African Onion Plant
Crinum calamistratum
Afzel's Anubias
Anubias afzelii
Anacharis
Egeria densa
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Belinda's Buce
Bucephalandra belindae
Fish Similar to Lake Eacham Rainbowfish
Lake Wanam Rainbowfish
Glossolepis wanamensis
A critically endangered species (IUCN Red List) endemic to Lake Wanam in Papua New Guinea. Known for the extreme deep-bodied shape and metallic green-bronze colors that mature males develop. They are fast, active schooling fish that require hard, alkaline water and plenty of swimming space. Excellent for large planted aquariums.
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.
Ajamaru Rainbowfish
Melanotaenia ajamaruensis
A highly active, schooling rainbowfish endemic to the Ayamaru Lakes in West Papua, Indonesia. Currently listed as Critically Endangered in the wild. It is closely related to Boeseman's Rainbowfish but possesses a notably more slender body and more prominent reddish-brown horizontal striping. They thrive in hard, alkaline water with dense vegetation and require significant horizontal swimming space.
Crimsonspotted Rainbowfish
Melanotaenia duboulayi
A highly active, schooling freshwater fish endemic to eastern Australia, often considered the original 'Australian Rainbowfish' in the aquarium trade. Recognizable by a prominent crimson red spot on the operculum (gill cover) and striking silvery-blue to greenish bodies. They are peaceful but extremely vigorous swimmers, requiring plenty of horizontal swimming space and a tight-fitting lid to prevent jumping.
Exquisite Rainbowfish
Melanotaenia exquisita
A highly active, schooling species native to the fast-flowing, clear streams of Australia's Northern Territory. True to their name, they display stunning metallic bodies with bright red-tipped fins. They require pristine, well-oxygenated water, plenty of horizontal swimming space, and should always be kept in groups of 6 or more.
Banded Rainbowfish
Melanotaenia trifasciata
A large, robust, and highly active schooling fish native to Northern Australia. Famous for its intense geographic color variations (such as the red 'Goyder River' morph). They are peaceful but incredibly fast and vigorous swimmers, requiring long aquariums with plenty of open swimming space.