Tag Archives: Gymnotus

Gymnotus carapo

19. June 2020

The number of scientifically described species in the genus Gymnotus increases rapidly recently. Since the last complete revision of the New World Knifefishes by Francisco Mago-Leccia in 1994 34 new species and 7 subspecies have been described, raising the total number of known species to 43. Members of the genus Gymnotus are cylindrical shaped and most often they have a quite attractive pattern. The maximum size that can be reached depends on the particular species. The smallest ones are said to reach only 10 cm, the largest up to 40 cm.

The Banded Knifefish (Gymnotus carapo) is the first species that became known to science and been described already back in 1758. The species has an enormous distribution in South America; however, one should keep in mind that many mis-identification probaly have appeared in elder literature. Gymnotus carapo belongs to the larger species of the genus. In 2017, 7 new subspecies of G. carapo have been described. The specimens from Venezuela, which we have currently in stock, belong to the subspecies Gymnotus carapo septentrionalis. In some specimens the banded pattern becomes a spotted pattern when they grow larger than about 20 cm. Smaller specimens are all banded. Maybe the pattern shows the sex in larger specimens?

Principically speaking Gymnotus carapo would make excellent aquarium fishes – despite the size they can grow. They species inhabits often swamp areas, has an accessory breathing organ and is very undemanding, has a very attractive pattern and swims – like all knifefishes – in a fascinating way. But sadly all Gymnotus are extremely aggressive against conspecifics. This makes it most often impossible even to keep a pair together. External differences between the sexes are unknown for Gymnotus. That is really a pity, because breeding Gymnotus would make a great project. Gymnotus are paternal broodcarer. From the wild, nest-building males have been described, in captivity they proofed to be mouthbrooders. Most probably sibling, but different speces were involved in the two studies.

Currently we have very nice specimens from Venezuela in stock. The fish are between 12 and 15 cm long and all banded, with one exception, a large spotted specimen, 25-30 cm long. Doesn´t that make a good opportunity to try the species?

For our customers: the fish have code 255204 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photos: Frank Schäfer

Gymnotus chaviro

22. June 2018

More and more species of Gymnotus become known to science. Gymnotus chaviro originates from Peru. Here it inhabits the basin of the upper Rio Jurua. The species is found together with its close relative G. carapo. The pattern of G. chaviro is species-specific. However, there is one usefull feature mentioned in the original description: the anal fin in G. chaviro is grey and black in G. carapo. This enables hobbyists to distinguish the two species, as it is very likely that they are at least occasionally collected and imported together.

The largest specimen of G. chaviro known so far was 27.5 cm long. In the original description (Maxime & Albert, 2009) a very interesting note can be found: sometimes G. chaviro can be seen in groups in the natural habitat! This could mean that this knife fish is rather peaceful against conspecifics and that there is a chance to keep several specimens together. All other species of Gymnotus imported so far proofed to be quite aggressive and could be kept singulary only. However, there are still no published observations on the aquarium biology of G. chaviro.

For our customers: the fish have code 255184 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photos: Frank Schäfer