Opsarius koratensis

28. June 2024

Typical open water fish are very rarely kept in the aquarium. There is a simple reason for this: they are usually quite colorless. The Opsarius koratensis, which can grow to a maximum length of 10-12 cm (some sources even state 16 cm), is no exception. However, keeping these fish can still be very rewarding, as Opsarius koratensis are real “eye-catchers” in sufficiently large aquaria because they are extremely lively. 

The animals form a hierarchy among themselves; they should therefore be kept in as large a group as possible, from about seven specimens upwards. Opsarius are completely unproblematic when it comes to feeding. Due to their extreme agility, however, they have a high nutritional requirement and should therefore be fed several times a day. Scientific studies have shown that Opsarius koratensis prefers warmer water (around 30°C). However, the species is still very lively even at 22°C. Opsarius koratensis is indifferent to other species of fish, although slower species are easily coming too short when feeding. Plants are ignored. The chemical composition of the water is relatively unimportant, but the water should not be markedly acidic; pH values in the neutral to slightly alkaline range should be aimed for.

Opsarius koratensis is relatively widespread in Southeast Asia and colonizes the river systems of the Mekong, the Chao Phraya and the Xe Bangfai (Thailand, Cambodia, Laos and parts of China). Clear to turbid, but always flowing waters are the species’ habitat. 

For our customers: the fish have code 439913 on our stock list. Please note that we only supply the wholesale trade.

Text & photos: Frank Schäfer