Lambchop Rasbora Breeding Guide

Breeding Trigonostigma espei: sexing, the inverted leaf-spawning unusual for cyprinids, soft acidic conditions, and rearing fry.

Overview

Trigonostigma espei is a small copper-orange cyprinid of around 2-3 cm, predominantly found in Thailand and Cambodia, with a further population on the island of Phu Quoc, Vietnam. It is named after the dark band that runs along its body like a lamb chop. The species is closely related to the harlequin rasbora and, like it, spawns in an unusual way for the family: rather than scattering eggs at random, the pair attaches eggs to the underside of broad leaves.

Sexing

Females are usually rounder-bellied and often a little larger than the slimmer, more colourful males. The dark wedge marking on the flank differs between the sexes: in males its outline is sharper and better defined, while in females it has a rounder appearance.

Breeding Setup

Use very dim lighting and either a bare base or a mesh that lets eggs pass through; plastic grass matting also works. Include broad-leaved plants such as Microsorium or Cryptocoryne, or artificial alternatives, as the spawning surface, with an optional small air-powered sponge filter.

Spawning Behavior & Trigger

Conditioned pairs adopt an inverted position beneath a broad leaf or other object as eggs and sperm are released, and the eggs are attached to the underside of that surface. Soft, acidic water of pH 5.0-6.0 and 1-5 degrees hardness at the upper end of the temperature range (toward 28 C) supports spawning.

Egg & Fry Care

Incubation usually takes between 24 and 48 hours, and the fry become free-swimming in around a week. Start them on Paramecium, then introduce Artemia nauplii and microworm once they are large enough.

Common Challenges

The very small first-feeding fry require an infusoria-grade culture, and dim conditions plus soft acidic water are needed to get eggs to develop, making this an intermediate-level project. The species itself is listed as Least Concern on the IUCN Red List, so captive breeding mainly serves the hobby rather than conservation.