Cobia (Rachycentron canadum)—also known as black kingfish, black salmon, ling, lemonfish, crabeaters, aruan tasek, etc.—are perciform marine fish, the sole representative of their family, the Rachycentridae.
 Attaining a maximum length of 2 metres (78 inches) and maximum weight of 68 kilograms (150 pounds), cobia have elongate fusiform (spindle shaped) bodies and broad, flattened heads. Their eyes are small and their lower jaw projects slightly 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, their dark brown coloration grading to white on the belly with two darker brown horizontal bands on the flanks. These may not be prominent except during spawning when cobia lighten in colour and adopt a more prominently striped pattern. The large pelvic fins are normally carried horizontally (rather than vertically as shown for convenience in the illustration), so that, as seen in the water they may be mistaken for a small shark. When boated, the horizontal pelvic fins enable the cobia to remain upright so that their vigorous thrashing can make them a hazard. The first dorsal fin is composed of six to nine independent, short, stout, and sharp spines. The family name Rachycentridae, from the Greek words rhachis meaning "spine" and kentron meaning "sting," is an allusion to these dorsal spines. Mature cobia have forked, slightly lunate tail fins with most fins being a dark brown. They lack air bladders.
Cobia are pelagic and are normally solitary except for annual spawning aggregations; however they will congregate at reefs, wrecks, harbors, buoys and other structural oases. They may also enter estuaries and mangroves in search of prey.
Cobia feed primarily on crabs, squid, and other fish. Cobia will follow larger animals such as sharks, turtles and manta rays in hope of scavenging a meal. Cobia are intensely curious fish and show no fear of boats. Their predators are not well documented, but the dolphinfish (Coryphaena hippurus) is known to feed on immature Cobia. Shortfin mako sharks are known to feed on adult Cobia and have been seen by fishermen following Cobia during their annual springtime migration in the northern Gulf of Mexico.
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