The cobia (Rachycentron canadum) is a species of perciform marine fish, the only representative of the genus Rachycentron and the family Rachycentridae. Other common names include black kingfish, black salmon, ling, lemonfish, crabeater, prodigal son and black bonito.
Attaining a maximum length of 2 m (78 in) and maximum weight of 78 kg (172 lb), the cobia has an elongated, fusiform (spindle-shaped) body and a broad, flattened head. The eyes are small and the lower jaw projects slightly past the upper. Fibrous villiform teeth line the jaws, the tongue, and the roof of the mouth. The body of the fish is smooth with small scales. It is dark brown in color, grading to white on the belly with two darker brown horizontal bands on the flanks. The stripes are more prominent during spawning, when they darken and the background color lightens.
The large pectoral fins are normally carried horizontally, perhaps helping the fish attain the profile of a shark. The first dorsal fin has six to nine independent, short, stout, sharp spines. The family name Rachycentridae, from the Greek words rhachis ("spine") and kentron ("sting"), was inspired by these dorsal spines. The mature cobia has a forked, slightly lunated tail, which is usually dark brown. The fish lacks a swim bladder. The juvenile cobia is patterned with conspicuous bands of black and white and has a rounded tail. The largest cobia taken on rod and reel came from Shark Bay, Australia, and weighed 60 kg (135 lb). - Wikipedia