Rhizosomichthys totae (sometimes known as Greasefishin English) was a species of catfish (order Siluriformes) of the family Trichomycteridae, and the only species of the genus Rhizosomichthys. This fish grew to about 13.8 centimetres (5.4 in) and was endemic to Colombia where it occurred in the Lake Tota basin. It is listed as an critically endangered (possibly extinct) species by the IUCN Red List.