Cavasius Catfish

Mystus cavasius is among the most geographically widespread members of its genus, occurring throughout floodplains, rivers, and irrigation channels of India, Bangladesh, Nepal, and Myanmar. It tolerates a remarkably broad range of water conditions — from clear, fast upland tributaries to turbid, organically rich lowland channels — and this adaptability makes it one of the more forgiving large bagrids in captivity.

In the aquarium, M. cavasius is an active nocturnal predator that spends daylight hours tucked beneath logs or in caves. It grows to a respectable 40 cm and requires a large tank, but unlike the very largest Mystus relatives it does not demand public-aquarium-scale infrastructure. It readily accepts a wide variety of meaty and prepared foods.

This species is frequently confused with related Mystus species in the trade and hobbyist literature. Positive identification can be made by barbel length, body proportions, and country of origin. Despite the semi-aggressive tag, it rarely bothers fish too large to swallow and makes a characterful, long-lived resident of a large Asian river biotope.

Water: 22–28°C, pH 6.5–8.0, tolerant of moderate hardness; good filtration but very forgiving. Tank: 500 L minimum; root tangles, caves; low-moderate lighting. Feeding: Sinking pellets, frozen prawns, earthworms, small fish; feeds readily after dark. Breeding: Rarely documented in aquaria; possibly seasonal; no established captive protocols. Compatibility: Semi-aggressive; avoid small fish; suitable with other robust, similarly sized species.