Cobia is also a municipality in Dambovita county, Romania; See: Cobia, Romania

Cobia (Rachycentron canadum) - also known as black kingfish, black salmon, ling, lemonfish, crabeaters, etc. - are large, dark brown perciform marine fish found in tropical and subtropical waters worldwide (excluding the eastern Pacific Ocean). They are the sole representative of their family, Rachycentridae.

Attaining a length of 2 metres and a weight of 68 kilograms, cobia have elongate fusiform bodies and broad, flattened heads. Their eyes are small and their lower jaw projects past the upper jaw. On the jaws, tongue and roof of the mouth are bands of villiform (fibrous) teeth. Their bodies are smooth with small scales, the brown coloration grading to silver on the belly with two dark horizontal bands on the flanks.

The first dorsal fin is composed of six to nine short, independent sharp spines. The family name Rachycentridae, from the Greek words rhachis meaning "spine" and kentron meaning "sting," is an allusion to these dorsal spines (which make handling of cobia hazardous). Mature cobia have forked, lunate tail fins with most fins being a dark brown. They lack air bladders.

Cobia closely resemble and are most closely related to the remora of the family Echeneidae. Furthermore, remora are often seen with cobia in loose associations. Cobia are pelagic and normally solitary; however they will congregate at reefs, wrecks, harbours, buoys and other structural oases. They may also enter estuaries and mangroves in search of prey. Cobia are powerful fish popular among sport fishermen, and a prized table fare.

Cobia fingerlings in aquaculture.

Crabs, squid and other fish make up the principal diet of cobia. Observed feeding behaviour is akin to their remora cousins: cobia will follow larger animals such as sharks, turtles and manta rays in hope of scavenging a meal. Their predators are not well documented, but the dolphinfish (Coryphaena hippurus) is known to feed on immature cobia. Mako sharks are occasionally seen following schools of migrating cobia by fishermen, and are known to feed on adult cobia during their annual springtime migration in the northern Gulf of Mexico. Cobia are frequently parasitized by nematodes, trematodes, cestodes, copepods and acanthocephalans.

Cobia are pelagic spawners; that is, they release many tiny (1.2 mm) buoyant eggs into the water which become part of the plankton. The eggs float freely with the currents until hatching. The larvae are also planktonic, being more or less helpless during their first week until the eyes and mouths develop. Spawning takes place diurnally from April to September in large offshore congregations. Up to 20 individual spawns may take place in one season, with intervals of about one to two weeks. During spawning cobia lighten in colour and adopt a light striped pattern.

Juvenile cobia are patterned with conspicuous bands of black and white. Their tales are rounded rather than lunate. Males mature at two years and females at three years, both sexes leading moderately long lives of 15 years or more. They are oceanodromous, meaning seasonal migrations are undertaken in search of warmer climes.

Considered an excellent food fish, cobia are fished for commercially. However, they are caught only sporadically and usually as a bycatch owing to their solitary nature. They have been farmed in aquaculture for this reason. The meat is sold fresh, frozen and smoked.