First report of albinism in the South American catfish Imparfinis mirini (Siluriformes: Heptapteridae)

Abstract

Albinism is a genetic condition caused by an autosomal recessive gene that affects normal pigmentation in animals. In Neotropical freshwater fish fauna, albinism cases are extremely rare, with only 14 species recorded among more than 6000 described. Here, we describe the first reported case of albinism in the South American catfish Imparfinis mirini. The albino fish was collected in July 2016 with a seine net in a stream in southeast Brazil. Although albinism can decrease the chance of fish survival, the cryptic and nocturnal habits of this species and the low amount of piscivorous fish and birds in the stream may have favored its growth. Two possible explanations for the appearance of the albino fish are discussed: a genetic disorder caused by heavy metal contamination and the high endogamy rate in the fish population which could increase the chances of appearing deleterious genes.