The process illustrates the life cycle of river fish.
Overall, the whole process is natural, cyclical, and consists of 8 stages. It begins with incubation and ends with spawning eggs in the river. This process occurs in two habitats: the river and the ocean.
To begin with, roe is laid in the river, where it undergoes incubation before the young fish emerge. After that, for some period of time fish are rearing in freshwater and getting ready for the next step in life. Then, it is time to go from river to estuary, where fish will be estuary rearing. Next, this is the moment to migrate to the ocean for rearing areas, where aquatic animals will grow and mature. The moment has arrived to return back to river to spawn their own eggs. The whole cycle is completed when adult fish are ready for spawning and new eggs are laid.
