Product Details

Aru Rainbowfish – Melanotaenia picta

Overview:

The Aru Rainbowfish is a colourful and active freshwater rainbowfish from the Aru Islands of Indonesia. Also known as the Painted Rainbowfish or Aru II Rainbowfish, Melanotaenia picta is a peaceful shoaling species that develops its best colour as it matures, especially when males and females are kept together in a well-maintained group. It is a superb choice for a spacious planted or stream-style community aquarium with clean water, open swimming space and calm tank mates.

Key Identification:

Common Name: Aru Rainbowfish
Other Names: Painted Rainbowfish, Aru II Rainbowfish, Aru Rainbow Fish
Scientific Name: Melanotaenia picta
Fish Type: Rainbowfish
Water Type: Freshwater

Natural Range & Habitat:

The Aru Rainbowfish is known from the Mareremar River system on Kobroor Island, part of the Aru Islands, Indonesia. FishBase describes its habitat as small rainforest brooks with clear water, quiet pools and cascades, with stream channels made up of smooth limestone and plenty of shelter from fallen logs and branches.

This natural habitat suggests a fish that appreciates clean, oxygen-rich water, moderate flow, open swimming areas and structured cover rather than stagnant or heavily polluted conditions.

Appearance & Adult Size:

Aru Rainbowfish have the deep-bodied, laterally compressed shape typical of many Melanotaenia species. Mature males usually show the strongest colour, with a mix of metallic body tones, warm orange to reddish highlights and contrasting fin colour depending on mood, age and lighting. Females and young fish are usually more subtle, but they are important for natural group behaviour and encouraging male display.

Adults reach around 9–11 cm, with FishBase listing males to 9.32 cm standard length and females to 7.91 cm standard length. Aquarium Glaser notes that the species grows to about 11 cm in aquarium care.

Aquarium Suitability:

This is an excellent fish for a peaceful, spacious community aquarium. Aru Rainbowfish suit planted aquariums, larger mixed rainbowfish displays and river-style setups with open swimming room. They are active midwater swimmers, so they should not be kept in small tanks, cramped aquascapes or aquariums with very shy fish that may be unsettled by constant movement.

They look especially good in groups against darker décor, with hardy planting around the sides and back while leaving clear space through the centre of the tank.

Recommended Aquarium Size:

A practical minimum is 180 litres for a group, with a tank length of at least 100–120 cm recommended. Larger aquariums are better for mixed rainbowfish communities or larger groups, as this species is active and displays best when it has room to swim.

Water Conditions:

Temperature: 22–26°C
pH: 6.8–7.8
Hardness: Moderately hard preferred; avoid very soft unstable water
Additional Notes: Provide clean, well-oxygenated water with good filtration and regular water changes. Aquarium Glaser recommends water that is not too soft, a neutral pH and a temperature of 22–26°C for this species. Moderate flow is appreciated, but avoid forcing the fish to constantly battle very strong current.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Aru Rainbowfish are peaceful, active shoaling fish. Suitable tank mates include other peaceful rainbowfish, larger tetras, peaceful barbs, danios, rasboras, Cory-type catfish, bristlenose plecs, peaceful gouramis and other robust community fish that enjoy similar water conditions.

Avoid aggressive cichlids, fin-nipping species, very tiny fish and slow, delicate tank mates that may be intimidated at feeding time. Keep in a group of at least 6, with 8 or more preferred. A mixed-sex group is best, as males usually show stronger colour and display behaviour when females are present. Fishkeeper also notes that colours improve with age and are best when both sexes are present.

Feeding:

Aru Rainbowfish are straightforward omnivores. Offer quality flakes, small floating or slow-sinking granules and rainbowfish pellets as the staple diet. Supplement with frozen or live foods such as daphnia, brineshrimp, cyclops, bloodworm and mosquito larvae. Include some vegetable or algae-based foods to round out the diet. Feed small portions that the group can consume quickly, as rainbowfish are fast feeders and can outcompete quieter species.

Behaviour in the Aquarium:

This species is an active upper to midwater swimmer that spends much of the day moving in a loose group. Mature males may display to each other with intensified colour and raised fins, especially in the morning or after water changes. They are peaceful rather than aggressive, but their constant movement means they are best housed with confident community fish. A secure lid is recommended, as active rainbowfish can jump if startled.

Care Notes:

Keep in a mature aquarium with stable water quality, good oxygenation and regular maintenance. Do not keep singly or in pairs, as small numbers can become nervous and less colourful. Avoid very soft acidic conditions if they are unstable, and avoid cramped tanks where males cannot display naturally. Young fish may arrive looking modest, but colour improves with age, condition and correct group structure.

Recommended For:

Beginner to intermediate

Availability:

Occasional / Specialist rainbowfish import or captive-bred when available

Image Disclaimer:

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Natural variation in size, colour, pattern and markings can occur between individual fish.