Trichomycteridae

Trichomycteridae is a family of catfishes, commonly known as the pencil or parasitic catfishes. They are native to the Neotropics, ranging from southern Mexico to the southernmost tip of South America. This family is characterized by its diverse range of forms and habits. Many species are small and slender, resembling pencils, while others are more robust.

A notable characteristic of some Trichomycteridae species is their parasitic nature. These fish often attach themselves to larger fish, feeding on blood and mucus. This behavior is particularly well-known in the genus Vandellia, with Vandellia cirrhosa, the candiru, being infamous for its alleged habit of entering the urogenital openings of humans. However, scientific evidence for this latter claim is scarce and often anecdotal.

The diet of non-parasitic species varies, including invertebrates, algae, and detritus. Trichomycterids inhabit a wide array of freshwater environments, from fast-flowing streams and rivers to stagnant pools and swamps. Their cryptic coloration and small size often make them difficult to find, and many species are known from only a few specimens.

Reproduction in Trichomycteridae is not well-studied for most species. However, some species are known to lay eggs in crevices or among vegetation. The family is part of the order Siluriformes, which includes many other families of catfishes. Despite their diverse adaptations, including the extreme specialization of some parasitic species, Trichomycteridae remains a poorly understood family with many species yet to be described.