For most of my life I have known the dwarf gourami as Colisa lalia but I have noticed that recently it is normally referred to as Trichogaster lalius .
And the gouramis previously in the genus Trichogaster (such as the blue gourami, pearl gourami, snakeskin gourami etc) are now classified in the genus Trichopodus
Until 1923, Trichogaster was used as the genus for the small gourami species and Trichopodus for the larger species. When the genus Trichopodus was established by Lacepede in 1801, it was not usual to designate a type species (as it is now), and later ichthyologists frequently designated one. A "type species" is the species that exhibits all the scientific characteristics for that genus, normally today the first such species to be described, and all species assigned to that genus will also share those characteristics. Topfer & Schindler (2009) detail the matter of the type species designations and errors respecting Trichogaster and Trichopodus; the end result was that in 1923, Dr. George S. Meyers incorrectly assumed the type species earlier assigned for Trichogaster and consequently established Trichogaster as the true genus in place of Trichopodus (which name became a synonym for Trichogaster) for the larger gourami species. Colisa was then selected as the genus for the small (dwarf) species previously assigned to Trichogaster.
This state remained (although in the literature there was frequent confusion) until 1997 when E. Derijst pointed out the error of the assumed type species by Meyers [see Topfer 2008]. R. Britz (2004) obsoleted the name Colisa, but its popularity continued in the literature. In 2008, J. Topfer thoroughly investigated the issue and recommended renaming of the species and K.-H. Rossmann (2008) followed. In 2009, Topfer & Schindler established Trichopodus as a currently valid genus of Osphronemidae, which includes the large gourami species, Trichopodus trichopterus, T. leerii, T. microlepis, T. cantoris and T. pectoralis. The Colisa species reverted back to the genus Trichogaster as Trichogaster chuna, T. fasciata, T. labiosa, T. lalius, and T. bejeus. The species epithets of this genus were also corrected grammatically in accordance with the rules of the ICZN [Schindler 2009]. The California Academy of Sciences--Ichthyology [W.N. Eschmeyer] has adopted the afore-mentioned revisions.
