Salmon go through several stages in their life before they are considered adults. A salmon is called an alevin, a fry, a parr and a smolt before it is considered an adult.
It takes about four years for a salmon to reach maturity since it must go through many stages of growth before it can swim in salt water. When a salmon egg hatches, the young is called an alevin and still depends on the yolk sac for nutrition. After 5 or 10 weeks, the salmon is called a fry and begins to look like a typical fish. After several months, when the fish has developed its tiger-like markings, it is known as a parr. Finally, after about 3 years, the parr ages into a smolt, which is the last stage of life before adulthood.