It can be distinguished from congeners by its small adult size and presence of a single solid dark midlateral stripe on the body, above which is a series of dark blotches forming a second stripe. In the similar but larger, T. schalleri the upper stripe is more variable depending on the mood of the fish, sometimes fading entirely.

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.

P. deissneri was the only recognised member of the genus for almost a century following its description in 1859.

As a result its name has and continues to be widely misapplied in both aquarium and ichthyological literature although it’s probably always been very rare in the hobby, while a number of fishes previously identified under the name from other pa…

This species is also referred to as ‘Kretser’s paradisefish’ and ‘spotted gourami’.

There exist three colour forms, two of which exhibit a greater degree of reddish or violet pigmentation in the fins, respectively. The third is more bluish and was described as M. kretseri minor by Deraniyagala (1958).

M. spechti is also sometimes referred to as M. concolor, particularly in older literature. A dispute regarding conservation of that name was resolved by the ICZN in 2006, however, since M. concolor Ahl, 1937 is a junior primary homonym of M. concolor Schreitmüller, 1936 and thus permanently invalid.

M. ocellatus can be distinguished from congeners by the following combination of characters: caudal-fin rounded; eye stripe not connecting spot on posterior projection of opercle with eye; dorsal-fin rays filamentous posterior to a vertical through the posterior anal-fin rays in adults; 16-19 spinous dorsal-fin rays; 6-13 rakers on ceratobranchial of first gill arch; posterior tip or margin of body scales not darker than scales.

M. opercularis is a classic aquarium fish, having been introduced to the hobby by a French soldier named Gerault in 1869. Of the initial 100 specimens shipped, 22 survived and were successfully bred later that same year by another Frenchman, the Parisian Pierre Carbonnier. This gives the species the distinction of being one of the very first ornamental fish imported to Europe. It is also known as ‘Chinese fighting fish’, ‘paradise gourami’, and ‘blue paradise fish’.

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…

This species lends its name to the Betta foerschi group of closely-related species within the genus, of which members share the following set of characters: possession of iridescent blue or green unpaired fins; rays and interradial membranes in unpaired fins not contrasting; dorsal fin with thin, bright white distal band; opercle with two, reddish-yellow, vertical bars.

Members are regarded as being closely-related to bubble nesting Betta specie…

This species occasionally appears in the ornamental trade where it is sometimes referred to as ‘blue tiger piranha’

Following Fink and Macaht can be distinguished from other members of the genus by the following combination of characters: body shape deep and rhomboid; head robust, snout blunt; eye large; mouth moderate, jaw projecting; 1-3 ontogeneticlly var…