Blue Hillstream Trout

About

Sold occasionally in the trade under the name 'blue hillstream trout', Opsarius bernatziki is a sleek, active cyprinid from the rivers of the Malay Peninsula. Its most recognizable features are the six or seven bluish vertical bars running down each flank and a distinctly colored blotch at the base of the tail fin. A combination that sets it apart from most of its close relatives, which either lack that tail-base marking or carry longer barbels. Like most fish in this genus, it is built for fast water and fast living: an exceptionally quick swimmer and an aggressive competitor at feeding time. This makes it a poor fit for a typical community setup. Slow, timid, or delicate tankmates will be outcompeted at mealtimes, and very small fish risk being treated as snacks. Robust, similarly-sized cyprinids and active bottom-dwellers tend to be the best companions. Despite being gregarious, this species forms a social hierarchy rather than a tight school, so a group of five or more is important. Smaller groups often result in the lower-ranked fish being harassed relentlessly. Given its need for active, confident tankmates and high-flow conditions, it suits a dedicated hillstream-style setup more than a general community tank. Breeding in captivity has not been documented.