Before reaching adulthood, salmon pass through a number of developmental phases. Before becoming an adult, a salmon is referred to as an alevin, a fry, a parr, and a smolt.
It takes around four years for a salmon to attain maturity, as it must pass through numerous phases of development prior to being able to swim in salt water. When a salmon egg hatches, the hatchling is known as an alevin and continues to rely on the yolk sac for sustenance. After 5 to 10 weeks, the salmon is referred to as a fry and begins to resemble a mature fish. After a number of months, when the fish has developed tiger-like stripes, it is referred to as a parr. After around three years, the parr matures into a smolt, the final stage of life before adulthood.