Large New Fish Species, a Piranha Relative, Found in Brazil

This is a male Myloplus zorroi, a new fish species discovered in the Madeira river basin, which flows into the Amazon. Douglas Bastos

Researchers have discovered a new species of fish in a tributary of the Amazon River, in western Brazil. The new fish has been named Myloplus zorroi, after the fictional character Zorro.

Fish in this genus, the taxonomic grouping above species, are known as pacus in the Amazon region. They are also in the same family as piranhas, but unlike those carnivores they feed on seeds, fruit and vegetation. They are also an economically important species, unlike piranhas, and often sought after by fishermen. Some pacus can reach lengths of three feet and weigh more than 50 pounds.

The first specimen of the new fish was first discovered in 2007, but it wasn't clear what species it was, and was originally taxonomically misplaced by other researchers. Analysis by scientists from Brazil's Federal University of Pará placed it in the Myloplus genus, based on its body plan, and unique teeth, which are specialized for grinding seeds.

The new species reaches more than 18 inches in length, and lives in moderate- to fast-moving streams that flow over rocky and sandy soil. It has a reddish color but yellow fins and belly, according to a study describing the finding, published March 7 in the journal ZooKeys.

The study authors chose the species's name as a reference to the legendary Latin American hero, but also out of respect to renowned ichthyologist Mauricio Camargo-Zorro.