Discus fish are famous for producing a slime-coated skin layer that their young eat.
Discus fish of the genus Symphysodon provide unusually intensive parental care. After hatching, their fry feed on mucus secretions produced by the skin of both parents. The secretion contains nutrients and supports the young during their early development, when they remain close to the adults.
This behavior is sometimes compared with nursing in mammals, but it is not milk production. Discus are cichlids native to slow-moving waters of the Amazon Basin. Their round, laterally compressed bodies and vivid patterns have made them popular aquarium fish, while captive breeding has produced many color varieties not commonly seen in wild populations.