Lambchop Rasbora Care Guide - Aquarium Setup, Diet & Breeding

The Lambchop Rasbora is a small, elegant schooling fish with a translucent golden to copper-coloured body and a distinctive black, wedge-shaped marking along its flank. The marking is often edged with orange or red, creating the lambchop-like pattern that gives this species its common name.

These rasboras are active but peaceful, spending much of their time in the middle and upper areas of the aquarium. In a group, they display more natural confidence and often form a loose school, with males becoming especially colourful when they court or establish brief social displays.

In the wild, Trigonostigma espei is associated with quiet, shallow waters surrounded by dense marginal growth. Leaf litter, submerged roots and overhanging plants create a dim, sheltered habitat, and the water may be clear, tea-coloured or lightly stained by decomposing vegetation.

Lambchop Rasboras are sometimes confused with the closely related Harlequin Rasbora, but they are generally slimmer and more delicately marked. Their small adult size, attractive pattern and gentle temperament have made them a favourite for planted community aquariums and nano-style displays.

Lambchop Rasboras are native to mainland Southeast Asia, particularly Thailand and Cambodia, including the eastern Gulf of Thailand region. They inhabit slow-moving streams, forest pools and small peat-influenced waterways with abundant vegetation and leaf litter.

A group of Lambchop Rasboras should have an aquarium of at least 45 litres, with a footprint of roughly 60 by 30 cm or larger. Use gentle filtration and leave open swimming space among dense planting, floating plants, fine roots and small pieces of driftwood. A dark sand or fine-gravel substrate helps their colours stand out, while leaf litter and subdued lighting can recreate the sheltered character of their natural habitat. Keep the aquarium mature, stable and securely covered, as these small rasboras can jump when startled.

Males reach about 3 cm (1.2 inches), while females may grow to approximately 3.5 cm (1.4 inches) in length.

Lambchop Rasboras are small omnivores that benefit from a varied diet. Offer a quality crushed flake or fine micro-pellet as a staple, supplemented with live or frozen daphnia, baby brine shrimp, cyclops and bloodworm in appropriately small portions. Occasional tiny insect larvae and other suitably sized foods help maintain their colour and condition. Feed little and often so food does not accumulate around the substrate.

Lambchop Rasboras are peaceful community fish and can be kept with other similarly sized, non-aggressive species. Suitable companions include celestial pearl danios, small peaceful tetras, pygmy Corydoras, Otocinclus, kuhli loaches, sparkling gouramis and other gentle rasboras. Avoid large or boisterous fish, fin-nippers and predatory species, which may intimidate them or treat them as prey. They should not be housed with aggressive cichlids or other fish that dominate the aquarium.

Lambchop Rasboras are egg scatterers that can breed in a mature, densely planted aquarium. Condition the adults with plenty of small live or frozen foods, then provide broad-leaved plants or a spawning mop, ideally in soft, slightly acidic water. The pair or group will scatter adhesive eggs among the leaves, after which the adults should be removed because they may eat the eggs. Hatching usually occurs within 24 to 48 hours, and the tiny fry need infusoria or another suitably small first food before moving on to freshly hatched brine shrimp.

Females are usually slightly larger, fuller-bodied and deeper through the abdomen than males. Males tend to be slimmer and may show stronger orange-red colouration and a more intense contrast around the dark lateral marking, particularly when displaying.