Green Slender Rasbora Care Guide - Aquarium Setup, Diet & Breeding

The Green Slender Rasbora is a long-bodied, streamlined cyprinid with a silvery to olive-green sheen. A dark lateral marking runs along the body, while the transparent fins and slender profile give this active fish an understated, elegant appearance. Colour can become more noticeable when the fish is relaxed or displaying among its companions.

Rasbora daniconius is native to South Asia, including parts of India, Sri Lanka, Bangladesh, Nepal and Pakistan. It occurs in freshwater streams, rivers, pools and other gently flowing waters across the Indian subcontinent.

A group should have at least a 100-litre aquarium, with a footprint around 90 x 30 cm or larger to provide room for sustained swimming. Use a secure lid, open swimming space and gentle to moderate water movement, along with efficient filtration and stable, well-oxygenated water. A dark, fine-grained substrate, hardy plants, driftwood and some shaded areas help the fish feel secure, while leaving the central area open for schooling.

Up to about 10 cm (4 inches) in total length. Females are usually slightly deeper-bodied and may be marginally larger than males, which commonly remain closer to 7–8 cm (2.8–3.1 inches) in aquarium conditions.

They are opportunistic omnivores that feed on small insects, crustaceans and other tiny invertebrates in nature, along with plant matter and fine organic debris. In an aquarium, offer a quality small-pellet or flake food supplemented with frozen or live daphnia, brine shrimp, mosquito larvae and other suitably sized foods. Several small meals help ensure that every fish receives food in a busy group.

Green Slender Rasboras are peaceful community fish and are well suited to groups of similarly sized, non-aggressive species. Suitable companions include peaceful barbs, danios, larger rasboras, small peaceful gouramis, many tetras and bottom-dwellers such as Corydoras and kuhli loaches. Avoid large predatory fish, fin-nippers and boisterous species that may intimidate them or treat them as prey.

Green Slender Rasboras are egg-scattering fish that can be bred in a separate, mature breeding aquarium with gentle filtration, fine-leaved plants or spawning mops, and subdued lighting. Condition a group with plentiful live or frozen foods, then introduce well-matched adults. They scatter adhesive eggs among vegetation, after which the adults should be removed because they may eat the eggs. Hatching generally occurs within roughly 24 to 48 hours, and the tiny fry initially require infusoria-sized food before progressing to newly hatched brine shrimp.

Females are generally fuller through the abdomen, particularly when carrying eggs, and may be slightly larger overall. Males tend to be slimmer, with a more streamlined profile and sometimes stronger colour during courtship.