Otocinclus affinis

Lore & Background

Otocinclus affinis is a herbivorous, rheophilic, bottom-feeding catfish that reaches a standard length of 5 cm. It is endemic to southeastern Brazil, specifically northern Rio de Janeiro state and the Ribeira de Iguape River in São Paulo state. The species is a Batesian mimic of Corydoras nattereri, and due to its narrow stripe, it resembles this Corydoras species more than it does other Otocinclus species. In the aquarium hobby, the name Otocinclus affinis is often used for close relatives that are employed for algae control, but these actually belong to the species O. vittatus, O. vestitus, O. macrospilus, and O. huaorani. The real O. affinis is rare in the aquarium hobby and is not as hardy as many other Otocinclus species.

Reader's Guide

The golden otocinclus holds significance primarily as a case of taxonomic confusion in the aquarium trade. While many small suckermouth catfishes sold under the name Otocinclus affinis are actually other species used for algae control, the true O. affinis is rare in the hobby. Its natural habitat preferences include fast-moving water, sandy substrate, and plenty of hiding areas such as old broken clay pipes. It prefers slightly acidic water with a temperature range of 21–27 °C. The species is not as hardy as many other Otocinclus species, making it less suitable for typical community aquariums. Its status as a Batesian mimic of Corydoras nattereri adds to its biological interest, as its narrow stripe makes it resemble that species more than its own congeners. The species is endemic to a limited area in southeastern Brazil, underscoring its restricted natural distribution.

Did You Know?

• The real O. affinis is rare in the aquarium hobby, despite the name being commonly used for other species.
• It prefers fast-moving water, sandy substrate, and hiding areas like old broken clay pipes.