Mystacoleucus atridorsalis

Overview

Mystacoleucus atridorsalis is a Mekong cyprinid identified in part by a triangular dark mark at the dorsal-fin tip. It uses flowing channels and enters flooded forest seasonally. A small spine ahead of the dorsal fin can catch in nets during transfers.

Distribution & habitat

It is considered restricted to the lower Mekong region of Laos, Thailand, and Cambodia, including the Xe Bang Fai, Mun, and Songkhram systems. Records assigned to it from central and western Thailand were misidentifications and should not automatically extend its range.

Flowing lowland channels are favored. During the wet season it also enters inundated forest and floodplain areas. Collections include faster forest streams over gravel.

Diet & feeding

Wild fish are generalist omnivores, consuming aquatic invertebrates, organic detritus, and algae. Their appearance should not lead to classification as exclusive algae eaters.

Notes

The triangular dorsal-tip blotch, crescent-shaped dark edges on some scales, and dark dorsal and caudal margins form useful combined identification clues. Usually only one weakly developed pair of barbels is present.

The genus has a forward-directed spine just before the dorsal fin. It can be difficult to notice yet still catch in mesh. If entanglement occurs during a transfer, do not pull forcefully on the fish.