Taxonomy & naming
Knight, Rai, D'Souza & Vijayakrishnan described the species in 2015 as Barilius ardens. It is now placed in Opsarius, with the authority in parentheses. Opsarius is a genus of stream-dwelling cyprinids of South and Southeast Asia, formerly included in Barilius, with an elongate body and a wide mouth suited to taking insects at the surface.
Morphology
A slender stream fish that FishBase gives at a maximum of 3.5 in SL. The name ardens means burning or glowing, which may refer to its colour.
Habitat
It is known from the Sita-Swarna river system of the Western Ghats in Karnataka, and FishBase lists it as a freshwater, benthopelagic fish of tropical water. Water parameters have not been published.
Feeding
Opsarius are active surface and midwater predators of insects that fall on the water, taking small invertebrates and sometimes small fish. The diet of this species has not been described separately.
Mating
Mating behaviour has not been described.
Breeding
Captive breeding has not been documented.
In the aquarium
Keep it in a long tank with strong flow, high oxygen, cool to moderate temperatures and a tight lid, since these fish jump. Keep a group, and give small live, frozen and floating foods. Care notes come from the genus.
Conservation
The IUCN Red List category is Data Deficient, assessed in 2021. That means there is too little information to judge extinction risk. Threats have not been described.