Harlequin Rasbora

About

The harlequin rasbora (Trigonostigma heteromorpha) is one of those species that has been in the hobby for well over a century and still earns its place in almost any peaceful community tank. Native to forest streams, peat swamps, and slow-moving waters across the Malay Peninsula, Singapore, and parts of Indonesia, these fish are accustomed to soft, often tea-colored water under dense canopy cover. In the aquarium they adapt reasonably well to a wider range of conditions, though they truly come into their own in a well-planted setup. The body is pinkish with a broad, dark triangular wedge running from below the dorsal fin toward the tail. Wider and more distinctly triangular than in the closely related T. espei or T. hengeli, which can cause some confusion at the fish store. Being a schooling species, harlequins genuinely need company. A group of eight to ten individuals is a sensible minimum. In smaller numbers they tend to be skittish, but a proper-sized school moves together with a confidence that looks great in the tank. They mix well with other small, peaceful fish including tetras, dwarf cichlids, loaches, and shy anabantoids. Mass-produced specimens can be somewhat washed out compared to wild fish, but healthy, well-fed individuals show good color, especially males competing for female attention.