Fish represent one of the groups with the largest number of migratory species. The main reason for migration is reproduction, but they can also migrate to feed or due to climatic conditions. Migrations can be within the same river basin, across the ocean, from sea to rivers, or from rivers to sea, depending on the fish species.

Some of the fish that are bred in captivity, in the wild, are migratory such as salmon, tuna, gilt-head bream, tilapia or pangasius.

Salmons:

Are born in fresh water, migrate to the oceans when they reach maturity, spend their adult lives in the sea, and return to the river to spawn.

The Atlantic salmon (Salmo salar), which is the one that is raised in fish farms, can travel up to 6,000 km from its river of origin to the feeding areas in the Atlantic Ocean (temperate and arctic regions).

When it reaches a certain weight, it migrates across the ocean, mainly through Greenland, back to the river where it was born, which may be on both, the American and European sides of the Atlantic Ocean.

After spawning, most die, but some survive and repeat the migration towards the ocean and back to the river to reproduce for the 2nd time.

Bluefin Tunas:

They perform extensive migrations between Atlantic feeding areas and breeding sites, either in the Gulf of Mexico (the western population), or in the Mediterranean (the eastern population).

They spend the winter feeding in the North Atlantic and in spring migrate to breed in the warm waters of the Mediterranean and the Gulf of Mexico. In summer, after spawning, they return to the Atlantic in search of food.

Like the Salmon, it presents a return behavior to the place of birth and fidelity to the breeding area.

Gilt-head Bream:

They present trophic migrations, especially the fry that are born in the open sea and migrate in early spring towards protected coastal waters, such as brackish water lagoons, estuaries and coastal areas, where they have more resources to feed and milder temperatures..

They remain in these areas until mid-autumn, when they begin to migrate to deeper areas, where adult fish breed.

Adults also frequent coastal areas during the summer, migrating to depths greater than 30 m in winter.

Tilapias:

Although a freshwater species, it inhabits and successfully colonizes brackish waters. So, they can migrate between fresh and salt water, to feed or hibernate.

Pangasius:

It migrates upstream of rivers in search of refuge in the dry season, to later return downstream to spawning, feeding and nursery habitats when the rains arrive, following the annual Monsoon cycle.