Cod is a species of white fish that is found in the cold seas near the 0º, in large shoals at depths of 50 metres to 600 metres, although it usually swims at depths of around 150 to 200 metres. It is found mainly in the North Atlantic. Fresh cod is cod that is caught from the end of autumn until spring, although nowadays it is possible to buy cod all year round as it is available in a variety of formats: dry salted; dried; fresh; smoked; and frozen.
Salmon live most of their lives in the sea before swimming to the upper reaches of freshwater rivers to spawn. For this reason they are considered to be a diadromous species. In the wild salmon remain in the seas of the northern hemisphere while they are growing, and reproduce in its lakes and rivers. It is very unusual for salmon to return to the sea after spawning, as they die of exhaustion. However, Atlantic salmon can return to the sea 2 or 3 times before they die.