饰妆低线鱲

Overview

Opsarius ornatus is an active river fish that needs substantial swimming room and well-oxygenated water. Its identity deserves attention before purchase: trade labels and historical locality records have confused it with relatives, so an apparently wide reported range can be misleading.

Distribution & habitat

It occurs in Thailand, but its precise range remains disputed. One interpretation restricts it to a few systems in Chumphon Province on the eastern Isthmus of Kra, especially the Tha Sae basin. Another places the original locality in the Chao Phraya system, where subsequent collections have not confirmed it. Reported habitats include flowing streams and rivers over sand, gravel, or mud.

Aquarium setup

Arrange sand, gravel, rounded stones, and wood around a generous open swimming area. Hardy attached plants can be included. Provide established filtration, ample oxygen, and moderate circulation; replace roughly one-third to one-half of the water weekly. An immature aquarium is unsuitable. Fit a secure cover and close equipment gaps because these fish can jump.

Diet & feeding

Members of this genus chiefly hunt aquatic and terrestrial insects at the surface, with small fishes and bottom invertebrates possibly supplementing the diet. Combine suitable prepared foods with live or frozen Artemia, bloodworms, and chopped earthworms. Feed fruit flies or small crickets nutritious food before offering them to the fish.

Behaviour & compatibility

Its speed and competitive feeding can overwhelm timid or slow companions, while very small fish may be eaten. Select robust partners of similar size. Keep at least five: a pair or trio can leave the weakest fish under sustained pressure, and an isolated individual may harass other similarly shaped fishes.

Sexual dimorphism

Females tend to be larger, fuller, and less colorful, especially when carrying eggs. Mature males apparently develop tiny tubercles on the head, body, and fins, together with reddish-orange or bronze color along the underside.

Notes

Older records from the Salween, Ataran, Ping, and Mekong involve another related species. An absent or small caudal-peduncle mark and short, slender barbels can assist identification, but neither one marking nor a dealer's label provides a secure diagnosis.