Eastern Rainbowfish
Melanotaeniidae sp.
The Eastern Rainbowfish (Melanotaeniidae sp.) is a peaceful fish that's a good step up once you have a little experience. Give it a tank of at least 190 litres (50 US gallons), water held at 75-84°F, and a pH of 6.5-8. Always keep a group of at least 6 - they feel safest in numbers.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
Australia / New Guinea
- Australia & Oceania
Regional colours match the stocking calculator's origin map.
Eastern Rainbowfish Tank Setup
Give them a tank of at least 190 litres (50 US gallons). As open-water swimmers they care more about swimming length than height, so a longer tank is ideal. Keep the water at 75-84°F with a pH around 6.5-8, and avoid sudden swings. Always keep a group of at least 6 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour. They reach about 15 cm as adults, so don't be misled by the small juveniles sold in stores.
What Do Eastern Rainbowfish Eat?
They're not fussy eaters - feed a varied diet, rotating good-quality dry, frozen, and gel foods rather than the same thing every day, and match the food size to their mouths.
Eastern Rainbowfish Tank Mates
Keep in groups of at least 6. The Eastern Rainbowfish is peaceful, which is the first thing to weigh up when you choose tank mates. It's a shoaling fish, so settle a group of 6 or more of its own kind before adding anything else - a stressed, lonely fish is far more likely to nip or hide. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Eastern Rainbowfish Good for Beginners?
Doable once you test water regularly and catch problems before fish look sick. If this is your first tank, pick something more forgiving and come back later.
Eastern Rainbowfish - frequently asked questions
What size tank do Eastern Rainbowfish need?
Eastern Rainbowfish need a tank of at least 190 litres (50 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Eastern Rainbowfish should I keep together?
Keep a group of at least 6. Eastern Rainbowfish are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Eastern Rainbowfish need?
Keep them at 75-84°F with a pH of 6.5-8, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Eastern Rainbowfish eat?
Eastern Rainbowfish are omnivores and aren't fussy eaters. Feed a varied mix of good-quality dry, frozen, and gel foods, and match the food size to their mouths. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Eastern Rainbowfish good for beginners?
Eastern Rainbowfish are best for keepers with a little experience. They are manageable once you test water regularly and catch problems early; a complete beginner may prefer something more forgiving first.
Common mistakes with Eastern Rainbowfish
- Buying fewer than 6 - Eastern Rainbowfishs need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
- Underestimating tank size - the minimum footprint is 190 litres (50 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Eastern Rainbowfish
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- Pea PufferPredator - Pea Puffer will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
