Juvenile fish go through various stages between birth and adulthood. They start as eggs which hatch into larvae. The larvae are not able to feed themselves, and carry a yolk-sac which provides their nutrition. Before the yolk-sac completely disappears, the tiny fish must become capable of feeding themselves. When they have developed to the point where they are capable of feeding themselves, the fish are called fry. When, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling. Fingerlings are typically about the size of fingers. The juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish.