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Care guide · Freshwater · fish

Clown Rasbora

Rasbora kalochroma

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The Clown Rasbora (Rasbora kalochroma) is a strikingly coloured, peaceful shoaling fish from Southeast Asia. Adults are pinkish to reddish with two dark blotches on each flank. The markings vary by locality and may fade under stress. Reaching about 10 cm standard length and swimming actively, this species needs substantial room as a group. Use a mature aquarium with stable water quality, open swimming space and a securely fitting lid. Keep at least eight to ten together. After feeding, check that all fish get enough food. Do not change water chemistry abruptly.

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At a glance

Temperature
23–28 °C
pH
5.0–7.5
GH
2–10 °dGH
Aquarium length
At least 120 cm
Minimum aquarium volume
At least 243 L
Adult size
At least 10 cm
Group size
At least 8–10 individuals
Temperament
Peaceful

About this species

Seriously Fish lists a maximum of about 10 cm standard length; FishBase also gives 10 cm, but as total length. These measures are not identical and are not converted. Two dark flank blotches and the reddish body help identify the species. Rasbora elegans is generally more silver, while R. kottelati has an extra dark blotch near the tail base. Juvenile clown rasboras may resemble Boraras maculatus. Pattern intensity varies and alone is not a reliable health indicator.

Natural habitat

The species occurs on the Malay Peninsula, Borneo and Sumatra. It mainly inhabits streams and rivers in peat-swamp forests. Decomposing leaves and wood stain the water with tannins; it is often soft and acidic, with low light beneath the forest canopy. A suitable aquarium may include roots, leaf litter, shaded areas and subdued lighting. Maintain good water quality and prevent organic waste from accumulating.

Aquarium and layout

For an active group, Seriously Fish recommends at least about 120 × 45 × 45 cm, roughly 243 litres. A long footprint and open swimming space matter; volume alone is not a guarantee. Keep the fish in a mature, stable aquarium and secure the lid carefully because it may jump. Wood, plants, shaded areas and leaf litter offer cover. Filtration and maintenance must handle the waste load of a larger group.

Water conditions

The specialist aquarium profile gives 23–28°C, pH 5.0–7.5 and GH 2–10 dGH. Natural peat swamps can be even softer and more acidic, but that does not mean every aquarium should reproduce those conditions. Ask about stock origin, acclimate carefully and avoid sudden changes. An immature aquarium and unstable water are unsuitable.

Behaviour and group size

The Clown Rasbora is peaceful and social. Keep at least 8–10; a sufficiently large shoal reduces nervousness and supports natural behaviour. Choose companions by adult size, temperament and feeding competition. The Brilliant Rasbora may suit under conditions: Seriously Fish records both in Endau blackwaters and their care ranges overlap. Provide generous space and stable water. Avoid tiny tank mates that could become prey.

Feeding

In nature the species feeds mainly on aquatic and terrestrial invertebrates. Offer quality dried food in suitably sized flakes or granules, varied with live or frozen foods such as bloodworms, Daphnia and Artemia. Small varied meals support condition and colour. Check that all fish can feed and remove leftovers promptly.

Breeding

The species scatters eggs and shows no parental care. A mature, densely planted aquarium may occasionally produce a few fry, but adults eat eggs they find. Deliberate breeding requires a separate tank where eggs fall beyond the parents’ reach. Larvae initially need very fine food. Success and yield depend on conditions and cannot be guaranteed.

Sources & review

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

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