The aim of this thesis is to present tunas, a group of marine fishes, members of the family Scombridae. The tunas are the most highly evolved of the scombrids and among the 14 species of tuna, bluefin tunas (Atlantic, Pacific and southern bluefin tuna), yellowfin tuna, skipjack, albacore and bigeye, are often referred as principal market tuna species. The bodies of all the fishes in this family are robust, elongate and streamlined. They prefer life near the surface of tropical, subtropical and temperate oceans and seas. Important environmental parameters for these fishes are the quantity of dissolved oxygen, the sea surface temperature and the salinity. Tunas are excellent swimmers and they must swim constantly to stay alive and to satisfy oxygen requirements. They move to search for food or for the purpose of reproduction, migrations are seasonal movements. Among all bony fish, the tunas are unique in ability to regulate their body temperatures. Atlantic bluefin tuna is one of the high value aquaculture species. Atlantic bluefin tuna farming in the Mediterranean is more relevant to call „fattening“. In 2016, the life cycle of this species in captivity, was closed for the first time.