The diagrams illustrate the life cycle of salmon, one of large fish species. Overall, it can be seen that this species originally hatch in fresh water, then life in the sea when adult. The stage of its development can be predicted by its length.
The life cycle of salmon begins in the river. Salmon eggs are laid between reeds and small stones in upper river in which the water moving slowly. These eggs then hatch, and the fry swims to the lower area of fast flowing river and lives there for about 4 years. Once the fry becomes smolt, it swims to the open sea and lives there for 5 years approximately. In mating season, adult salmon swim back to the upper river where they originally come from, to lay their eggs. Then this cycle is continued.
The body size of salmon represents its developmental stage. A 3 - 8 cm sized salmon is called the fry. After growing for about 12 - 15 cm long, the fry is called smolt. Salmon can be considered as adult fish after it reaches at least 70 cm in length.
The diagrams below show the life cycle of a species of large fish called the salmon
