Tiger Hillstream Loach (Sewellia pterolineata) Breeding Guide

Genus-level breeding guide for Sewellia pterolineata, a striped hillstream loach, based on documented Sewellia spawning and sexing.

Overview

Sewellia pterolineata is a hillstream loach of the genus Sewellia, family Gastromyzontidae. The genus is native to Laos and Vietnam, occurring in shallow, fast-flowing, highly oxygenated headwaters and tributaries with rocky substrates. According to Seriously Fish, Sewellia are among the easiest hillstream loaches to breed in captivity, often spawning within mature, well-maintained groups.

Sexing

Females have a comparatively broad body with a snout running almost continuously into the pectoral fins. Males are slighter, with a much squarer snout and pectoral fins emerging at almost right angles. Mature males develop rows of soft, raised tubercles on the anterior portion of the first five to six pectoral-fin rays, plus additional rows on the head.

Breeding Setup

Adults are kept as a group in shallow, fast-flowing, highly oxygenated water over rounded river gravel with nooks and crannies. These crevices allow eggs to settle and remain protected from predation, reproducing the rocky-stream conditions of the natural range.

Spawning Behavior & Trigger

Courtship is male-initiated: the male circles, mouths the female's dorsal surface and pushes to move her into open water. The pair then rise into the water column with pectoral fins entwined and release eggs and milt directly into the flow where the current is strongest. Raising the temperature to 25-26 °C (77-79 °F) followed by cool water changes can act as a spawning trigger.

Egg & Fry Care

Eggs develop within the gravel. Fry are first fed infusoria, then Artemia nauplii and microworm. Fry may remain with the adult group once they reach around 5 mm in length.