Otocinclus travassosi is endemic to the São Francisco River basin in eastern Brazil — a major river system geographically and faunistically isolated from the Amazon and Paraná basins, and consequently home to a high proportion of endemic fish species. Named after the Brazilian parasitologist Lauro Travassos, O. travassosi is one of a small number of Otocinclus species restricted to this drainage. It displays a clean lateral stripe pattern and subtle dorsal reticulations.
The São Francisco River and its upper tributaries drain the semi-arid interior of northeastern Brazil, producing water that is moderately hard and slightly alkaline compared to Amazonian rivers — a notable departure from the soft, acidic conditions typical of most Otocinclus habitat. O. travassosi is consequently one of the few species in the genus adapted to harder, more alkaline conditions, though the upper headwaters where it likely occurs may be softer.
In the aquarium, O. travassosi is primarily of scientific and collector's interest. Its potential tolerance of slightly harder water compared to Amazonian congeners makes it interesting from a care perspective. Standard Otocinclus maintenance applies, with attention to replicating the somewhat harder water chemistry of the São Francisco drainage if maximum health and colour are desired.
