Swim-up fry

From Biology-Online Dictionary | Biology-Online Dictionary

Swim-up fry

(Science: marine biology) life stage that begins when the alevin (larval salmonid) has absorbed its yolk sac, and begins to swim upward to emerge from the gravels where eggs were deposited. The swim-up stage is viewed as a distinct life stage because the air bladder is not yet inflated, and the fish are negatively buoyant. They struggle to swim upward toward the water surface, and then gulp air to fill the air bladder. The swim-up stage ends once the air bladder is filled, and the juveniles are referred to simply as 'fry.'