FishA fish (: fish or fishes) is an aquatic, craniate, gill-bearing animal that lacks limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period.
Forage fishForage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes (herrings, sardines, shad, hilsa, menhaden, anchovies, and sprats), but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.
Shoaling and schoolingIn biology, any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. In common usage, the terms are sometimes used rather loosely. About one quarter of fish species shoal all their lives, and about one half shoal for part of their lives. Fish derive many benefits from shoaling behaviour including defence against predators (through better predator detection and by diluting the chance of individual capture), enhanced foraging success, and higher success in finding a mate.
Recreational fishingRecreational fishing, also called sport fishing or game fishing, is fishing for leisure, exercise or competition. It can be contrasted with commercial fishing, which is professional fishing for profit; or subsistence fishing, which is fishing for survival and livelihood. The most common form of recreational fishing is angling, which is done with a rig of rod, reel, line, hooks and any one of a wide range of baits, as well as other complementary devices such as weights, floats, swivels and method feeders, collectively referred to as terminal tackles.
Fish as foodMany species of fish are caught by humans and consumed as food in virtually all regions around the world. Fish has been an important dietary source of protein and other nutrients throughout human history. The English language does not have a special culinary name for food prepared from fish like with other animals (as with pig vs. pork), or as in other languages (such as Spanish pez vs. pescado). In culinary and fishery contexts, fish may include so-called shellfish such as molluscs, crustaceans, and echinoderms; more expansively, seafood covers both fish and other marine life used as food.
Fish finFins are distinctive anatomical features composed of bony spines or rays protruding from the body of Actinopterygii and Chondrichthyes fishes. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as seen in sharks. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles. Their principal function is to help the fish swim.
GrouperGroupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes. Not all serranids are called "groupers"; the family also includes the sea basses. The common name "grouper" is usually given to fish in one of two large genera: Epinephelus and Mycteroperca. In addition, the species classified in the small genera Anyperidon, Cromileptes, Dermatolepis, Graciela, Saloptia, and Triso are also called "groupers." Fish in the genus Plectropomus are referred to as "coral groupers.
HerringHerring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, including the Baltic Sea, as well as off the west coast of South America. Three species of Clupea (the type genus of the herring family Clupeidae) are recognised, and comprise about 90% of all herrings captured in fisheries.
Pelagic fishPelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs. The marine pelagic environment is the largest aquatic habitat on Earth, occupying 1,370 million cubic kilometres (330 million cubic miles), and is the habitat for 11% of known fish species. The oceans have a mean depth of . About 98% of the total water volume is below , and 75% is below .
TunaA tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: , weight: ) up to the Atlantic bluefin tuna (max length: , weight: ), which averages and is believed to live up to 50 years. Tuna, opah and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water.