Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species.
For more information, see Wikipedia.

Salmon is the common name for several species of ray-finned fish in the family Salmonidae. Other fish in the same family include trout, char, grayling and whitefish. Salmon are native to tributaries of the North Atlantic (genus Salmo) and Pacific Ocean (genus Oncorhynchus). Many species of salmon have been introduced into non-native environments such as the Great Lakes of North America and Patagonia in South America. Salmon are intensively farmed in many parts of the world. Typically, salmon are anadromous: they hatch in fresh water, migrate to the ocean, then return to fresh water to reproduce. However, populations of several species are restricted to fresh water through their lives. Folklore has it that the fish return to the exact spot where they hatched to spawn. Tracking studies have shown this to be mostly true. A portion of a returning salmon run may stray and spawn in different freshwater systems; the percent of straying depends on the species of salmon. Homing behavior has been shown to depend on olfactory memory.
For more information, see Wikipedia.

Trout is the common name for a number of species of freshwater fish belonging to the genera Oncorhynchus, Salmo and Salvelinus, all of the subfamily Salmoninae of the family Salmonidae. The word trout is also used as part of the name of some non-salmonid fish such as Cynoscion nebulosus, the spotted seatrout or speckled trout. Trout are closely related to salmon and char: species termed salmon and char occur in the same genera as do fish called trout (Oncorhynchus – Pacific salmon and trout, Salmo – Atlantic salmon and various trout, Salvelinus – char and trout). Lake trout and most other trout live in freshwater lakes and rivers exclusively, while there are others, such as the steelhead, which can spend two or three years at sea before returning to fresh water to spawn (a habit more typical of salmon). Steelhead that live out their lives in fresh water are called rainbow trout. Arctic char and brook trout are part of the char family. Trout are an important food source for humans and wildlife, including brown bears, birds of prey such as eagles, and other animals. They are classified as oily fish.
For more information, see Wikipedia.

The barramundi (Lates calcarifer) or Asian sea bass, is a species of catadromous fish in family Latidae of order Perciformes. The species is widely distributed in the Indo-West Pacific region from Southeast Asia to Papua New Guinea and Northern Australia. Known in Thai language as pla kapong, it is very popular in Thai cuisine. It is also called bhetki by the people of Bengal and is a prized part of Bengali cuisine. Barramundi is a loanword from an Australian Aboriginal language of the Rockhampton area in Queensland meaning "large-scaled river fish". Originally, the name barramundi referred to Scleropages leichardti and Scleropages jardinii. However, the name was appropriated for marketing reasons during the 1980s, a decision which has aided in raising the profile of this fish significantly. L. calcarifer is broadly referred to as Asian seabass by the international scientific community, but is also known as Australian seabass.
For more information, see Wikipedia.

The Sparidae are a family of fish in the order Perciformes, commonly called sea breams and porgies. The sheepshead, scup, and red seabream are species in this family. Most sparids are deep-bodied compressed fish with a small mouth separated by a broad space from the eye, a single dorsal fin with strong spines and soft rays, a short anal fin, long pointed pectoral fins and rather large firmly attached scales. They are found in shallow temperate and tropical waters and are bottom-dwelling carnivores. There are hermaphrodites in the Sparidae. Protogyny and protandry appear sporadically through this lineage of fish. Simultaneous hermaphrodites and bi-directional hermaphrodites do not appear as much since Sparidae are found in shallower waters. Species of fish that express a hermaphroditic condition usually "lack a genetic hardwire", therefore ecological factors play a role in sex determination. Most species possess grinding, molar-like teeth. Some of the species, such as Polysteganus undulosus, have been subject to overfishing, or exploitation beyond sustainable recovery.
For more information, see Wikipedia.

The Atlantic mackerel (Scomber scombrus), also known as Boston mackerel, Norwegian mackerel, Scottish mackerel or just mackerel, is a species of mackerel found in the temperate waters of the Mediterranean Sea, the Black Sea, and the northern Atlantic Ocean, where it is extremely common and occurs in huge shoals in the pelagic zone down to about 200 m. It spends the warmer months close to shore and near the ocean surface, appearing along the coast in spring and departing with the arrival of colder weather in the fall and winter months. During the fall and winter, it migrates out into deeper and more southern water, seeking warmer temperatures. The Atlantic mackerel's body is elongate, steel-blue marked with wavy black lines dorsally and silvery-white ventrally, its snout long and pointed. It possesses two spiny dorsal fins, which are spaced far apart, two pectoral fins, and small caudal and anal fins, also spaced far apart. 4-6 dorsal finlets and 5 anal finlets are typical among members of this species. The fish's body tapers down its length, ending with a large tail fin. Typical size for a mature fish is 30 cm, but individuals have been caught as large as 60 cm. The maximum published weight is 3.4 kg. Reproduction, which is oviparous, occurs near the shore in the spring and summer, during which a female can produce as many as 450,000 eggs. Juveniles reach sexual maturity at around 2 years of age and can live to be 17.
For more information, see Wikipedia.

Swordfish (Xiphias gladius), also known as broadbills in some countries, are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish of the billfish category, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood. These fish are found widely in tropical and temperate parts of the Atlantic, Pacific, and Indian Oceans, and can typically be found from near the surface to a depth of 550 m. They commonly reach 3 m in length, and the maximum reported is 4.55 m in length and 650 kg in weight. Contrary to popular belief, the "sword" is not used to spear, but instead may be used to slash at its prey to injure the prey animal, to make for an easier catch. Mainly, the swordfish relies on its great speed and agility in the water to catch its prey. It is undoubtedly among the fastest fish, but the basis for the frequently quoted speed of 97 km/h is unreliable. Swordfish prefer water temperatures between 18 and 22 °C, but have the widest tolerance among billfish, and can be found from 5 to 27 °C. This highly migratory species typically moves towards colder regions to feed during the summer. Swordfish feed daily, most often at night, when they rise to surface and near-surface waters in search of smaller fish. During the day, they commonly occur to depths of 550 m and have exceptionally been recorded as deep as 2,878 m.
For more information, see Wikipedia.

The European bass (Dicentrarchus labrax) is a primarily ocean-going fish native to the waters off Europe's western and southern and Africa's northern coasts, though it can also be found in shallow coastal waters and river mouths during the summer months. It is one of only six species in its family, Moronidae, collectively called the temperate basses. It is both fished and raised commercially, and is considered to be the most important fish currently cultured in the Mediterranean. In Ireland and the United Kingdom, the popular restaurant fish sold and consumed as sea bass is exclusively the European bass. In North America it is widely known by its Italian name branzino. European bass can reach sizes of up to 1 m in length and 12 kg in weight, though the most common size is only about half of that at 0.5 m. Individuals are silvery grey in color and sometimes a dark-bluish color on the back. Juveniles form schools and feed on invertebrates, while adults are less social and prefer to consume other fish. They are generally found in the littoral zone near the banks of rivers, lagoons, and estuaries during the summer, and migrate offshore during the winter. Despite being a sought-after gamefish, it is listed as Least Concern by the International Union for the Conservation of Nature because it is widespread and there are no known major threats.
For more information, see Wikipedia.