E. caudiocellatus can be told apart from congeners by lacking a dark lateral stripe and possessing a prominent dark marking on the caudal peduncle.

In recent years a number of phylogenetic studies involving Esomus and its near relatives have been conducted and conflicting results published. For example a 2003 study by Fang et al. concluded that the genus is the sister group, i.e., most closely-related to…

Known from the Mekong river basin in Thailand, Laos, Cambodia, and Vietnam, the Tonlé Sap river and lake system in Cambodia, and smaller, coastal drainages in southeast Thailand. Records from Peninsular Malaysia are likely to refer to other species.

Type locality is given simply as ‘Cambodia’.

The adult size and power of this impressive predator preclude it from consideration as an aquarium species, but young individuals are nevertheless available in the ornamental trade on an irregular basis therefore it is included here.

It is an entirely unsuitable choice for the home aquarium and the majority of zoos and public aquaria would probably struggle to maintain it in adequate conditions.

The anatomical structure of miniaturised cyprinids can vary greatly; there are two putative groups with some species possessing intermediate features to some degree. The first contains those fishes which though small are essentially proportionally dwarfed versions of their larger relatives.

The other includes those in which anatomical development stops at a point where adult still resemble a larval form of their larger ancestor, as in…

As far as we know this species has not been bred in aquaria although Pete Liptrot and Paul Dixon of the Bolton Museum Aquarium, UK, have achieved great success with an unidentified congener. They first noticed fry from their group of 24 adults after moving the school to a dedicated set-up planted with mature Java moss and have since rewarded with regular batches of fry.

In the Mekong, it has been observed to migrate upstream from Phnom Penh to Khone Falls between November and February, returning downstream between May and August. The downstream migration ends in the Mekong delta area in Vietnam, where the fish remain until the floods reach their peak in October and November. These lower Mekong migrations mostly comprise juveniles and sub-adults, whereas above Khone Falls…

As with others in the genus little has been written regarding captive care of this species, but it makes a peaceful and unusual addition to larger aquaria. The best way of obtaining it may be to keep an eye on shipments of wild fishes from Indochina.

It can be distinguished from congeners by possessing 20 circumpeduncular scales and lacking barbels entirely.

It can be distinguished from congeners by possessing one or two pairs of barbels, a black blotch at the base of the caudal-fin, and rows of dark spots along the lateral scale rows.

Members of Cyclocheilichthys are characterised by possessing a serrated dorsal fin spine, 9 branched pelvic fin rays, a conical snout, small, subterminal…

Despite being a wholly unsuitable aquarium subject, C. idella is often traded as such, with an albino form having been developed specifically for the ornamental market.

Individuals which have outgrown their aquarium or pond should never be released into natural waters, either, since this species has proven capable of causing serious environmental damage under a wide range of climatic conditions.

This species can be most easily distinguished from other members of the genus by its colour pattern which consists of a blackish midlateral stripe extending from the tip of the gill opening to the middle of the caudal-fin base, which is separated from the dark brown dorsum by a pale yellowish brown stripe. This differs from the pattern seen in other Crossocheilus species with a black midlateral stripe in which the the dorsum is olive brown and much paler than the midlateral stripe, there is no yellow stripe between the dorsum and the black stripe, and the black stripe extends to the tip of the snout.