Fishing is the extraction of aquatic organisms from the environment in which they developed for various purposes, such as food, recreation (recreational fishing or sport fishing), ornamentation (capturing of ornamental species), or for industrial edible purposes, including the manufacture of animal feed for livestock and the production of substances of interest to health – such as the “famous” fish liver oil (especially cod liver oil).

Fisherman for leisure in the interior of Brazil
This definition encompasses the concept of aquaculture where captured species are first reared in appropriate facilities such as tanks, cages or ponds.

The main species exploited by fisheries in the world belong to the groups of fish, crustaceans and molluscs. However, several species of crocodiles, batrachians (mainly frogs), marine mammals (mainly whales) and algae are also cultivated and captured by humans.

According to “The State of Fisheries and Aquaculture in the World”, a publication of the FAO (United Nations Food and Agriculture Organization), the production of fish in the world in 2002 was over 94 million tons due to extractive activity. and another 50 million for aquaculture. It is estimated that fish currently supply about 16% of the protein consumed by humans. According to the UN agency for agriculture and food, exports reached the mark of US$ 136 billion in 2013; which reflects the strong growth of aquaculture and the high prices of several species of fish, such as salmon and shrimp. This year, by FAO's calculation, global fish production both in fisheries and in captivity reached a new record last year, of 160 million tons. Since 1950, fish catches have increased fivefold from 18 to 100 million metric tons per year. However, the numbers keep increasing. Fisheries are also a huge provider of employment, contributing enormously to the world economy.

Fish are vertebrate, aquatic, typically ectothermic animals, which have a fusiform body, limbs transformed into fins or flippers (absent in some groups) supported by bony or cartilaginous rays, gills or gills with which they breathe oxygen dissolved in water (although dipnoics use lungs) and, for the most part, the body covered in scales.