Khwae Yai

The Mae Klong chameleon catfish, Acrochordonichthys septentrionalis, is an akysid from western Thailand, possibly endemic to the Mae Klong drainage. It differs from other members of the A. ischnosoma group in its almost uniformly cream body with a few small brown spots, though colouration in the genus is variable. Like its congeners it can secrete a milky substance from the axillary pore when stressed, and this can quickly kill other fishes in an aquarium.

Discherodontus halei is a cyprinid with an apparently disjunct range: Pahang in Peninsular Malaysia, and the Mae Klong and Chao Phraya in Thailand. It inhabits clear, fast-flowing minor rivers and forest streams, and orange pigmentation in the dorsal and caudal fins helps separate it from congeners. Like others in the genus it is notoriously delicate and difficult to ship, losing scales very easily when removed from the water.

Opsarius signicaudus is a cyprinid known only from headwater tributaries of the Mae Klong River in western Thailand. It inhabits well-oxygenated, moderate to fast-moving rivers and streams over gravel, cobbles and boulders, and is intolerant of organic wastes. A large, elongated blotch at the caudal-fin base helps separate it from congeners. It may have been exported for aquaria, though probably not under the correct name.

The giant snakehead, Channa micropeltes, is a predatory fish from Southeast Asia that grows to well over a metre. Juveniles are sold as 'red' or 'redline' snakehead, but it is suitable only for public installations or the very largest private aquaria. Unlike most Channa species it is pelagic and needs plenty of room to swim, and adults become aggressive at sexual maturity.

Amblyrhynchichthys micracanthus is a riverine cyprinid from the Mekong catchment in Laos, Thailand, Cambodia and Vietnam, and the Chao Phraya system. It moves into inundated forest during the wet season, and wild fish feed on periphyton, plankton and benthic algae. Older records of A. truncatus from mainland Indochina all refer to this species, which has a straighter snout profile, a shorter dorsal-fin spine and fewer gill rakers.

Mystacoleucus chilopterus is a pelagic cyprinid from the middle Mekong, Chao Phraya and Mae Klong basins in Laos and Thailand. It favours flowing lowland rivers and swiftly-flowing forest streams with rock and gravel. The anal fin has a concave margin and the dorsal and caudal fins black margins, and like all Mystacoleucus it has a forward-pointing predorsal spine that can become entangled in an aquarium net.