This species is euryhaline and mostly inhabits brackish estuaries, coastal lagoons and the lower reaches of rivers.

It also occurs in freshwater habitats, however, including a number of inland lakes in Sri Lanka although it appears to have been introduced intentionally.

This species is readily available in the aquarium trade and is a good subject for those new to the hobby given its peaceable nature and relative adaptability in terms of water chemistry. It’s sold under various names including

A number of selectively-bred ornamental strains have also been produced including ‘red’, ‘sunset’, and ‘golden’, for which care is identical to the natural form.

This species isn't especially popular in the aquarium trade but is undoubtedly interesting despite its lack of colour. In addition to its survival ability in the absence of water it's also capable of producing audible sounds though the purpose of these has not been fully-studied. Naturally-occurring xanthic and albino forms have also been recorded.

There is considerable confusion as to the taxonomic status of the two species currently occupying this genus, with ichthyologists widely…

Generally considered to have an enormous natural range extending from Iran to Taiwan and Bali, with records existing from Iran, Iraq, Afghanistan, Pakistan, Nepal, India, Sri Lanka, Bangladesh, Bhutan, China, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Indonesia, and Singapore.

However there exists significant evidence to suggest that C. gachua as currently understood represents a complex of similar-looking species, and a taxonomic review of the group is clearly required.

D. polota is sometimes referred to as D. quadrifasciatus (Sevastianov, 1809) but the original name of the latter, Chaetodon quadrifasciatus Sevastianov, 1809, is a junior primary homonym of the older Chaetodon quadrifasciatus Bloch & Schneider 1801, thus Coius polota Hamilton, 1822 takes precedence.

C. bleheri is a popular aquarium fish though it remains unclear whether collection for the ornamentaol trade is having a detrimental effect on wild populations (see ‘Habitat’).

It’s one of several genus members to lack pelvic fins and can be further distinguished from other Channa species by the following combination of characters: sides of lower jaw with one large cycloid scale; lateral line complete with 46-50 scales; 14 pectoral-fin rays; 25 anal-fin rays; 4-11 irregular reddish orange markings on the caudal-fin

This species was available in the aquarium hobby for a number of years prior to description and continues to be traded under various names including C. sp. ‘Lal Cheng’, C. sp. ‘Assam’, C. sp. ‘blue bleheri’, C. sp. ‘himalayanus’, and C. sp. ‘red’.

The names of valid, but distinct, congeners such as C. amphibeus, C. bleheri or C. stewartii have also been misapplied to it.

This species is among the more well-known badids in the aquarium hobby, and is a popular choice for ‘nano’ aquaria since it is among the smallest percoid fishes known.

It is easily told apart from congeners since it is the only species in which males possess a series of seven iridescent blue vertical bars on the flanks.

Engmann (1909) mentions that the type series was collected from ‘Malakka’ but this is considered an error which probably should have read ‘Kerala’ since this species is known only from coastal drainages of the Western Ghats mountains in southern Kerala state, India.

This species is sometimes sold under the trade name of 'chameleon fish' due to its ability to rapidly change colour, especially when breeding or stressed. It was originally described as Labrus badis by Hamilton but Bleeker reclassified it as Badis buchanani in 1854; he had adopted the species name 'badis' as the new name for the genus and wished to avoid using a tautonym. At that time the use of tautonyms was avoided in zoological taxonomy but is now permissible under ICZN ru…