Not furry, but we like them anyway.
Dwarf Neon Rainbowfish
Melanotaenia praecox (Weber & de Beaufort, 1922)
Also called Dwarf rainbowfish, Neon rainbowfish, Diamond rainbowfish, Praecox rainbowfish, Peacock rainbowfish
From Mamberamo River system in northern West Papua (New Guinea), Indonesia.1234
At a glance the quick version
Usually up to about 5 cm standard length; occasionally up to 8 cm.
Looks how to spot one
Scales, compact rainbowfish
A small, deep-bodied rainbowfish; males develop a tall body even at only 3 to 3.5 cm. The scales give an iridescent neon-blue shine.134
Personality what they are like
Very peaceful and a little shy, becoming bolder in a group. Males spar and display to each other without real harm.23
Daily activity how busy a day looks
Lively swimmer that stays near the upper water layers and appreciates open space.32
Grooming and care the hands-on bits
Keep a lid on the tank because it can jump. Regular water changes and some live food help colour.32
Home where they are happiest
Minimum about 60 x 30 x 30 cm (around 54 litres). Temperature 22-29 C (sources vary: 22-28 C FishBase, 23-28 C Seriously Fish, 24-29 C ANGFA), pH 6.6-8.0, moderately hard water (about 5-15 dGH). Plenty of plants, including floating plants.2143
Food basics what goes in the bowl
Omnivore that accepts dried, frozen and live foods; live foods help bring out colour.23
Company who they like around
Keep in a shoal of at least 6 to 8. Good company includes other small rainbowfish, tetras, danios, small barbs, dwarf cichlids and Corydoras.21
The story where it all began
First collected in 1910 by W.C. van Heurn from a Mamberamo River tributary and described by Weber and de Beaufort in 1922. It entered the aquarium hobby around 1991-92 through collections by Charles Nishihira and Heiko Bleher.43
Fun facts for the dinner table
- 1
Males grow a notably deep, tall body while still tiny, at only about 3 to 3.5 cm long.1
- 2
It lives only in the Mamberamo system, one of New Guinea's longest rivers at over 2000 km.2
- 3
Newly hatched larvae can swim well straight away.4
- 4
Females can keep spawning for several days, scattering eggs among plants.3
- 5
Its wild streams are often only about 4 metres wide and half a metre deep, with slow flow over mud, gravel and leaf litter.4
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 6 December 2019)1
- Taxonomy
- Family Melanotaeniidae; described by Weber & de Beaufort in 1922, originally as Rhombatractus praecox3
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Dwarf Neon Rainbowfish. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at [email protected] and we will fix it.
- FishBase: Melanotaenia praecox summary fishbase.seused for origin, size, temperature, IUCN status, group size, body shape
- Seriously Fish: Melanotaenia praecox seriouslyfish.comused for care, tank size, water parameters, behaviour, diet
- Wikipedia: Melanotaenia praecox en.wikipedia.orgused for other names, colours, history, behaviour
- ANGFA Rainbowfishes: Melanotaenia praecox rainbowfish.angfaqld.org.auused for history, colours, size, water conditions
Checked 2026-09-30. Text is written in our own words from these sources.