Here's a breakdown:
* Alevins: This refers to the salmon young that are still absorbing their yolk sac. They are blind and stay in the gravel nests where they hatched.
* Fry: This is the stage after the alevins have absorbed their yolk sac and begin to actively swim and feed. They are still small and vulnerable.
Once the fry grow larger, they are referred to as parr. Parr are identifiable by the dark vertical bars on their sides. Finally, when they are ready to migrate to the ocean, they are called smolts.
Let me know if you want to learn more about any of these stages!