Rasbora vulcanus

Overview

Rasbora vulcanus is a small western Sumatran rasbora with striking sexual color differences. Males are orange-red and females pale yellow. Selecting only brilliant red individuals can produce an all-male group; pale females should not be dismissed as inferior fish or automatically assigned to another species.

Distribution & habitat

Confirmed locality information points to the Batang Si Joontour near Painan in West Sumatra, Indonesia. Regional endemism remains possible rather than proven. Collections apparently came from clear flowing streams.

The name refers to male redness, not a discovery beneath Mount Talang. A volcano trade label does not indicate a hot-spring habitat.

Aquarium setup

The listed minimum accommodation can house a group. Dense planting over a dark bottom improves the display, with floating plants, roots, and branches softening the light.

Avoid biologically immature systems because fluctuations in water conditions may cause problems. Fit a closely secured lid against jumping.

Diet & feeding

Minute insects, worms, crustaceans, and other plankton are considered likely natural prey rather than a confirmed specialized diet. Appropriate dry foods are accepted, but daily small live or frozen items such as Daphnia and brine shrimp support better condition.

Behaviour & compatibility

It is very peaceful with companions selected for appropriate size and requirements. Groups of eight to ten or more reduce nervousness and allow males to show stronger red during courtship competition.

Sexual dimorphism

Males carry orange-red pigment, strongest in dominant individuals. Females are pale yellow with only slight red in unpaired fins and usually become fuller and a little larger. Trade selection often favors colorful males, so verify the presence of females when forming a breeding group.

Breeding

It scatters eggs repeatedly and provides no care. For increased yield, use a dim, long, shallow container initially half-filled, with mesh or plastic grass separating eggs from the parents. Mildly acidic water toward the warmer end of the established suitable range is appropriate.

A small initial power filter can direct water along the container. Introduce one or two conditioned pairs, gradually top up with small additions of cooler water every few hours, and offer modest live or frozen feeds. Spawning usually occurs in the morning through several egg releases.

After a few days, remove adults and exchange powered filtration for a mature sponge unit to protect fry. Incubation generally lasts 18–48 hours, followed by another 24–48 hours to free swimming. Start with Paramecium or similar microscopic foods, then introduce brine shrimp nauplii and microworms as size permits.

Notes

It is often mislabeled Rasbora reticulata. That similar species comes from Nias, is deeper-bodied, and lacks the male red coloration. Both have dark scale margins, so a net-like pattern alone does not resolve identity.