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Care guide · Freshwater · fish

Brilliant Rasbora

Rasbora einthovenii

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The Brilliant Rasbora (Rasbora einthovenii), also known as the long-band rasbora, is an active and peaceful shoaling fish from Southeast Asia. It is more commonly seen in the aquarium hobby than many rasboras and is usually captive-bred for trade. Its body has a long dark lateral stripe with a notably uneven edge. Keep at least six together in a long aquarium with stable water quality and a secure lid: these fish can jump. Feed small portions and mature the aquarium biologically before adding the fish. Observe the shoal regularly, especially after acclimation, and follow a consistent maintenance routine.

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At a glance

Temperature
22–26 °C
pH
5.0–7.5
GH
2–10 °dGH
Aquarium length
At least 120 cm
Minimum aquarium volume
At least 108 L
Adult size
At least 9 cm
Group size
At least 6 individuals
Temperament
Peaceful

About this species

Seriously Fish lists a standard length of about 9 cm; FishBase reports 10.619 cm SL. The higher figure is used for space planning without treating the source measurements as identical. The dark lateral stripe often has a wavy or crinkled edge. It resembles Rasbora jacobsoni, but that species has dark reticulated scales above the stripe and is rarely encountered in trade. Pattern and colour can vary locally.

Natural habitat

The species occurs in southern Thailand, the Malay Peninsula, Singapore, Borneo and Sumatra. It is mostly found in dark forest streams and rivers associated with peat-swamp forest. Leaves and wood release tannins that stain the water and provide shade. Some populations also occur in clear water. A naturalistic setup is not a reason to change water conditions abruptly.

Aquarium and layout

Seriously Fish recommends at least about 120 × 30 × 30 cm, roughly 108 litres, for a group. Length and open swimming space matter more than volume alone. Use a biologically mature aquarium with stable water quality; the species may react poorly to swings in an immature tank. A dark substrate, wood, leaf litter, subdued light and plants that tolerate low light can provide shelter. Fit a secure lid.

Water conditions

The specialist species profile gives 22–26°C, pH 5.0–7.5 and GH 2–10 dGH. FishBase reports a narrower pH range of 6.0–6.5 for natural habitats, but populations do not all live under identical conditions. Many localities are soft and acidic. Avoid imposing one sharp target on every aquarium: consider stock origin, acclimate carefully and keep temperature, pH and hardness stable.

Behaviour and group size

The species is peaceful and should be kept with at least six conspecifics. A proper group reduces nervousness and allows more natural swimming behaviour. Choose tank mates by size, temperament and water needs; avoid large predators and fish that outcompete it for food. This active species needs ample horizontal swimming room. No individually verified compatibility relation is recorded yet, so general group guidance alone should not be treated as proof of a suitable pairing.

Feeding

Rasbora einthovenii is a micropredator that eats small insects, worms, crustaceans and other zooplankton. Offer fine live or frozen foods such as Daphnia and Artemia alongside dried food sized for its mouth. Dried food should not be the entire diet. Feed small portions and observe whether all fish eat enough. Remove leftovers before they harm water quality.

Breeding

The species scatters eggs and provides no parental care. Seriously Fish notes that breeding in the hobby is uncertain; fry may occasionally appear in a mature, densely planted aquarium. Adults eat eggs they find. A separate breeding setup with egg protection may help, but no fixed yield or success can be guaranteed. Newly hatched larvae need very fine starter food.

Sources & review

This care guide draws on several specialist sources and was last checked on .

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