Myloplus

The redhook, Myloplus rubripinnis, is a relative of the silver dollars from much of northern South America, including the Amazon and Orinoco. Commonly sold as a silver dollar, it can be told apart by its black-trimmed, red anal fin and grows much larger, to around 25 cm. Given a large enough aquarium, correct feeding and good water quality it should not pose many problems. It is still widely referred to as Myleus rubripinnis.

The black-barred myleus, Myleus schomburgkii, is a close relative of the redhook from parts of Venezuela, Peru and Brazil. The black vertical bar on the flanks distinguishes it, and it is a smaller adult fish, though it is sometimes offered for sale as a redhook. Also called the black-ear pacu and disc pacu, it should be kept in groups of at least five, and a tight-fitting lid is a good idea as it moves extremely quickly when startled.