The Brazilian guitarfish (Rhinobatos horkelii) is a species of fish in the family Rhinobatidae. It is endemic to Brazil, where its natural habitat is coastal waters on the continental shelf. This fish is viviparous and has a long gestation period, concluding with the birth of live pups in February. At this time the fish are subject to intense fishing activity but catches have been dwindling in recent years as a result of overfishing. Because so few breeding-size fish remain, the International Union for Conservation of Nature has assessed the fish's conservation status as being "critically endangered".