Rasbora lacrimula · Red Cherry Rasbora

Overview

Rasbora lacrimula is a tiny, peaceful rasbora with a faint dark lateral stripe ending in a teardrop-shaped tail-base mark. Larger fish develop small projections behind the dorsal fin and onto the upper tail edge. These features are more useful than cherry or dwarf-volcano trade labels.

Distribution & habitat

Confirmed records are limited to the Belayan drainage within the lower Mahakam system in Indonesian East Kalimantan. A wider regional distribution remains possible rather than established.

Collection sites include gutters and open-ground streams in a heavily modified oil-palm landscape. Clear water moves slowly over sand, clay, and mud. Earlier forest fires changed the area, so the recorded setting should not be described simply as intact primary forest.

Aquarium setup

Provide a footprint of at least around 45 × 30 cm. Dense plants over a dark bottom, or wood and leaves creating natural cover, help display its coloration. Floating vegetation softens the light.

Strong currents are unnecessary, but consistently clean water remains essential; gentle flow does not justify accumulating organic waste.

Diet & feeding

Small insects, worms, crustaceans, and other plankton are suggested natural prey. Dry foods of appropriate size are accepted, but should be supplemented daily with small live or frozen items such as Daphnia and brine shrimp to support condition and breeding readiness.

Behaviour & compatibility

It is very peaceful, with its minute adult dimensions especially important in choosing companions. Eight to ten or more reduce nervousness and let males show stronger colors during courtship competition.

Sexual dimorphism

Adult males tend to be smaller, slimmer, and more intensely colored than females.

Breeding

It scatters eggs repeatedly without care. A mature planted aquarium may retain a few fry, but greater yields call for a separate long, shallow container, initially half-filled and dimly lit. Mesh or plastic grass protects fallen eggs from the adults.

Use mildly acidic to neutral water, toward the warmer part of the established suitable range. An initial small power filter can direct flow along the tank. Add one or two conditioned pairs, then gradually top up with small additions of cooler water every few hours while offering modest live or frozen feeds.

Several releases usually occur, each yielding around 5–12 eggs, with 30–50 in a typical batch. After a few days, remove adults and replace powered filtration with a mature sponge unit to protect fry. Hatching takes about 18–48 hours, followed by another 24–48 hours before free swimming. Paramecium or similar microscopic food precedes brine shrimp nauplii and microworms as the young grow.

Notes

The small dorsal projections are inconspicuous in smaller fish and may relate to maturity; they should not alone be used for sexing. Their position and the teardrop-shaped tail marking together aid identification.