It’s not strictly necessary for fish-keepers to learn the scientific names of their fish but if a deeper understanding of the hobby is desired than some degree of knowledge is important, if only to better appreciate the relationships between different species. In addition the generic and specific names often contain information that is useful to know. When communicating with fellow fish-keepers on the internet knowing the correct name of the fish is even more important given the differing common names applied to aquarium fish throughout the globe.

Having said that, few things vex the amateur fish-keeper more than the constant changing of scientific names. It’s often cited as a barrier to learning them in the first place, after all what’s the point if some crazy taxonomist can change it at the drop of a hat? It is however one of the strengths of the scientific method that all conclusions remain provisional and that they can always be revised in the light of new data. If it were not so then mistakes would remain fixed and progress and understanding would be retarded. When the name of a favourite fish is altered we should look upon it as a learning opportunity and celebrate that we have become just a bit less ignorant!

The classification of fish species has been going on since Linnaeus published Systema Naturae in 1735 so it’s not surprising that some mistakes have been made along the way, even more so when it is understood that classification often comes down to one person’s opinion over another’s.

There are many ways that errors can occur apart from differences in opinion of course. A species may be described more than once, in which case the first description will take priority. An invalid name may be used or a name can be transcribed incorrectly and the error repeated in subsequent publications. New species can be discovered which shed new light on the relationship between existing species – necessitating a revision. Often times a review of existing literature will reveal historical errors that have been perpetuated over the years and it’s one such review that is the main subject of this article – the gouramis.

Gouramis are a group of Asian fish that have been a staple of the pet fish trade for decades. Their small size, attractive colours and peaceful nature have endeared them to generations of fish-keepers. They are deservedly popular and their willingness to breed in home aquaria has made them a very familiar fish to both serious and casual hobbyists. They are a relatively small group of fish and their scientific names are reasonably well-known amongst even new hobbyists. There are just two genera, Colisa, which has four species of small Indian gouramis and Trichogaster with four, slightly larger South-East Asian species.

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Colisa chuna	(Hamilton, 1822)	Honey gourami
Colisa fasciata	(Bloch & Schneider, 1801)	Banded gourami
Colisa labiosa	(Day, 1877)	Thick-lipped gourami
Colisa lalia	(Hamilton, 1822)	Dwarf gourami
Trichogaster leerii	(Bleeker, 1852)	Pearl gourami
Trichogaster microlepis	(Günther, 1861)	Moonlight gourami
Trichogaster pectoralis	(Regan, 1910)	Snake-skin gourami
Trichogaster trichopterus	(Pallas, 1770)	Three-spot gourami

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It hasn’t always been thus. Until 1923 the four small gouramis were classed as Trichogaster and the larger gouramis as Trichopodus. But Myers (1923) incorrectly determined that the type species of Trichogaster was not Trichogaster fasciata but Trichopodus trichopterus. Trichopodus was therefore made a synonym for Trichogaster and the new genus Colisa was erected for the four smaller species.

In 1997 Derijst pointed out the error and in 2004 Britz made Colisa obsolete and returned the eight species to their previous genera (resurrecting Trichopodus at the same time). With few exceptions the proposed changes were not used in subsequent literature. In 2008 however both Töpfer and Roßmann identified the changes by Derijst and in 2009 Töpfer and Schindler published a paper reaffirming Trichopodus as valid with the type species being Trichopodus trichopterus.

We examined the taxonomic papers about the type species fixation of the genus Trichopodus LACEPÈDE, 1801. As the result we found that under the current version of the ICZN the designation of the type species by BLEEKER (1879) is the valid one. Therefore, the type species of Trichopodus is Labrus trichopterus PALLAS, 1770. The genus Trichopodus is a currently valid genus of Osphronemidae, which includes the following species: T. trichopterus, T. leerii, T. microlepis and T. cantoris.

The whole paper can be read here.

The story does not end there though because in the same publication Hans-Joachim Paepke published a paper on the Snake-skin gourami – Trichopodus pectoralis. In this paper he laid out a convincing argument that the correct name for this fish should be Trichopodus cantoris. The abstract of the paper reads thus:

The Snake-Skin Gourami was described twice: First by GÜNTHER (1861) as Osphromenus (sic!) trichopterus var. ß cantoris. The name was used partly up to the early twenties of the last century. But already in 1905 KÖHLER elevated that taxon on species level as Osphromenus cantoris. REGAN (1910) described the same species again as Trichopodus pectoralis. Both authors (GÜNTHER and REGAN) stressed different (nuptial and non nuptial) colour pattern of the species. As Trichogaster pectoralis (REGAN, 1910) the species was known lasting for decades. With the newly reinstatement of the genus name Trichopodus for the Southeast Asian gourami species trichopterus, microlepis, leerii an cantoris the oldest name available for the Snake-Skin Gourami is Trichopodus cantoris (GÜNTHER, 1861). Trichopus cantoris SAUVAGE,1884 is most probably a junior synonym of Trichopodus leerii (BLEEKER, 1852), while Osphronemus (sic!) saigonensis BORODIN, 1930 is without question a junior synonym of Trichopodus cantoris (GÜNTHER, 1861).

The whole of Paepke’s paper can be read here.

**** UPDATE – 11th January 2010.  Paepke has published a correction, once again placing Trichopodus cantoris in synonymy with Trichopodus trichopterus. So the snake-skin gourami is still Trichopodus pectoralis. The paper with the correction can be read here.

A final complication is that the specific name of Colisa lalia has changed slightly in order to correct an earlier error and to conform to the rules of scientific nomenclature. The original description had it as Trichopodus lalius with lalius being the native name of the fish. This makes lalius a noun and specific names which are nouns do not change in gender to agree with the generic name. So it must always remain as lalius no matter what genus it is placed in. (If it had remained in Colisa it should correctly be known as Colisa lalius.)

All the changes are summarised in the table below.

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Old	New
Colisa chuna	Trichogaster chuna	Honey gourami
Colisa fasciata	Trichogaster fasciata	Banded gourami
Colisa labiosa	Trichogaster labiosa	Thick-lipped gourami
Colisa lalia	Trichogaster lalius	Dwarf gourami
Trichogaster leerii	Trichopodus leerii	Pearl gourami
Trichogaster microlepis	Trichopodus microlepis	Moonlight gourami
Trichogaster pectoralis	Trichopodus pectoralis	snake-skin gourami
Trichogaster trichopterus	Trichopodus trichopterus	Three-spot gourami

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Whether or not the changes are accepted quickly or gradually remains to be seen but there’s no doubt the new names are correct. Older aquarists will likely never take to them but provided the new names are used in all new works and in the popular trade magazines they should gain wider acceptance with the younger members of the hobby. The old names will gradually die out which in the case of Colisa at least will be a bit of a shame – it’s such a lovely name and I’ll be sad to see it go.

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References

1. Britz, R. 2004. Why Colisa has become Trichogaster and Trichogaster is now Trichopodus. AAGB Labyrinth 136, 8–9
2. Derijst, E. 1997. Nota over de geldigheid van de genusnamen: Trichogaster Bloch & Schneider, 1801; Trichopodus Lacepede, 1801; Polyacanthus CUVIER, 1829 en Colisa Cuvier, 1831 (Perciformes: Belontiidae)… Aquarium Wereld 60(9): 217–236
3. Rossmann , K.-H. 2008. Neue Namen für die Fadenfische? Der Makropode 30(3): 79–80
4. Schindler, I. 2009. On the spelling of the Species name of the genus Trichogaster (Formerly Colisa) and Trichopodus. Der Makropode 31(1): 5–9
5. Töpfer, J. 2008. Lacepède – 2. Teil: Seine Labyrinthfischgattungen Osphronemus, Trichopodus und Macropodus sowie die Gültigkeit der Namen. Der Makropode 30(2): 41–52