Freshwater fish in the context of "Fish hook"

The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land and freshwater fauna migrated from North America to South America via Central America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor, forming a land bridge between the previously separated continents. Although earlier dispersals had occurred, probably over water, the migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age. It resulted from the joining of the Neotropic (roughly South American) and Nearctic (roughly North American) biogeographic realms definitively to form the Americas. The interchange is visible from observation of both biostratigraphy and nature (neontology). Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians, arthropods, weak-flying or flightless birds, and even freshwater fish to migrate. Coastal and marine biota were affected in the opposite manner; the formation of the Central American Isthmus caused what has been termed the Great American Schism, with significant diversification and extinction occurring as a result of the isolation of the Caribbean from the Pacific.

The occurrence of the interchange was first discussed in 1876 by the "father of biogeography", Alfred Russel Wallace. Wallace had spent five years exploring and collecting specimens in the Amazon basin. Others who made significant contributions to understanding the event in the century that followed include Florentino Ameghino, W. D. Matthew, W. B. Scott, Bryan Patterson, George Gaylord Simpson and S. David Webb. The Pliocene timing of the formation of the connection between North and South America was discussed in 1910 by Henry Fairfield Osborn.

Several groups of tetrapods have undergone secondary aquatic adaptation, an evolutionary transition from being purely terrestrial to living at least partly aquatic. These animals are called "secondarily aquatic" because although all tetrapods descended from freshwater lobe finned fish (see evolution of tetrapods), their more recent ancestors are terrestrial vertebrates that evolved on land for hundreds of millions of years, and their clades only re-adapted to aquatic environment much later.

Unlike primarily aquatic vertebrates (i.e. fish), secondarily aquatic tetrapods (especially aquatic amniotes), while having appendages such as flippers, dorsal fin and tail fins (flukes) that resemble fish fins due to convergent evolution, still have physiology based on their terrestrial ancestry, most notably their air-breathing respiration via lungs (instead of aquatic respiration via gills) and excretion of nitrogenous waste as urea or uric acid (instead of ammonia like most fish). Nearly all extant aquatic tetrapods are secondarily aquatic, with only larval amphibians (tadpoles) being primarily aquatic with gills, and only some species of paedomorphic mole salamanders (most notably the fully aquatic axolotl) retain the gill-based physiology into adulthood.

Centrarchidae, better known as sunfishes or centrarchids, is a family of freshwater ray-finned fish belonging to the order Centrarchiformes, native only to North America. There are eight universally included genera within the centrarchid family: Lepomis (true sunfishes), Micropterus (black basses), Pomoxis (crappies), Enneacanthus (banded sunfishes), Centrarchus (type genus, consisting solely of the flier C. macropterus), Archoplites (Sacramento perch), Ambloplites (rock basses), and Acantharchus (mud sunfish). Their closest relatives are the pygmy sunfishes of the family Elassomatidae, which are sometimes placed in the same family, although presently treated as distinct.

The centrarchid family comprises 38 identified species, 34 of which are extant. It includes many popular game fishes familiar to North American anglers, such as the rock bass, largemouth bass, bluegill, pumpkinseed, green sunfish and crappies. Most sunfish are highly valued panfish for sport fishing, and have been introduced in many areas outside their native ranges, sometimes becoming invasive species. While edible, they are not commercially marketed as food fish.

The largemouth bass (Micropterus nigricans) is a carnivorous, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern and central United States, southeastern Canada and northern Mexico. It is known by a variety of regional names, such as the widemouth bass, bigmouth bass, black bass, largie, potter's fish, Florida bass or Florida largemouth, green bass, bucketmouth bass, green trout, growler, Gilsdorf bass, Oswego bass, southern largemouth and northern largemouth.

The largemouth bass, as it is known today, was first described by French naturalist Georges Cuvier in 1828. A recent study concluded that the correct scientific name for the Florida bass is Micropterus salmoides, while the largemouth bass is Micropterus nigricans. It is the largest species of the black bass, with a maximum recorded length of 29.5 inches (75 cm) and an unofficial weight of 25 pounds 1 ounce (11.4 kg).

The Amur River (Russian: река Амур) or Heilong River (simplified Chinese: 黑龙江; traditional Chinese: 黑龍江) is a perennial river in Northeast Asia, forming the natural border between the Russian Far East and Northeast China (historically the Outer and Inner Manchuria). The Amur proper is 2,824 km (1,755 mi) long, and has a drainage basin of 1,855,000 km (716,000 sq mi). If including its main stem tributary, the Argun, the Amur is 4,444 km (2,761 mi) long, making it the world's tenth longest river.

The Amur is an important river for the aquatic fauna of Northeast Asia. The river basin is home to a variety of large predatory fish such as northern snakehead, Amur pike, taimen, Amur catfish, predatory carp and yellowcheek, as well as several species of trout and anadromous salmonids. The largest fish species in the Amur is the kaluga, a sturgeon that is one of the largest freshwater fish in the world, attaining a length as great as 5.6 m (18 ft). The Amur is also home to the northernmost populations of the Amur softshell turtle and Indian lotus.

Trout (pl.: trout) is a generic common name for numerous species of carnivorous freshwater fishes belonging to the genera Oncorhynchus, Salmo, and Salvelinus, all of which are members of the subfamily Salmoninae in the family Salmonidae. The word trout is also used for some similar-shaped but non-salmonid fish, such as the spotted seatrout/speckled trout (Cynoscion nebulosus, which is actually a croaker).

Trout are closely related to salmon and have similar migratory life cycles. Most trout are strictly potamodromous, spending their entire lives exclusively in freshwater lakes, rivers and wetlands and migrating upstream to spawn in the shallow gravel beds of smaller headwater creeks. The hatched fry and juvenile trout, known as alevin and parr, will stay upstream growing for years before migrating down to larger waterbodies as maturing adults. There are some anadromous species of trout, such as the steelhead (a coastal subspecies of rainbow trout) and sea trout (the sea-run subspecies of brown trout), that can spend up to three years of their adult lives at sea before returning to freshwater streams for spawning, in the same fashion as a salmon run. Brook trout and three other extant species of North American trout, despite the names, are actually char (or charr), which are salmonids also closely related to trout and salmon.

Thymallus, commonly known as graylings, is a genus of freshwater ray-finned fish and the only genus within the subfamily Thymallinae of the family Salmonidae. Although all Thymallus species can be generically called graylings, without specific qualification the term "grayling" typically refers to the type species Thymallus thymallus, the European grayling.

The term carp (pl.: carp) is a generic common name for numerous species of freshwater fish from the family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized quarries and are valued (even commercially cultivated) as both food and ornamental fish in many parts of the Old World, they are considered trash fish and invasive pests in many parts of Africa, Australia and most of the United States.

An artificial fly or fly lure is a type of fishing lure, usually used in the sport of fly fishing (although they may also be used in other forms of angling). In general, artificial flies are an imitation of aquatic insects that are natural food of the target fish species the fly fishers try to catch. Artificial flies are constructed by fly tying, in which furs, feathers, thread or any of very many other materials are tied onto a fish hook.

Artificial flies may be constructed to represent all manner of potential preys to freshwater and saltwater fish, including aquatic and terrestrial insects, crustaceans, worms, spawn, small baitfish, reptiles, amphibians, mammals and even birds. Effective artificial fly patterns are said to be killing flies because of their ability to put fish in the creel for the fly fisher. There are thousands of artificial fly patterns, many of them with descriptive and often idiosyncratic names.