Cobia have brown backs, a darker stripe extending the length of their sides, and are white beneath. They have several small finlets ahead of their dorsal fin. When viewed from above, they appear distinctly shark-like. Very young cobia are darker and look remarkably like a sharksucker.

Cobia are not bashful feeders, chasing down food from the top to the bottom of the sea. They seem to especially prefer crabs. Cobia raised in captivity will not grow well unless they are fed some crabs and research indicates that over 70% of their diet is made up of swimming crabs, such as the blue crab. Researchers have found very few shrimp in their stomachs, but finfish were important. By far the most common were hardhead catfish, followed by eels, and then round scad. As cobia grow larger, a greater percentage of their diet is made up of finfish. Feeding seems to slow at lower water temperatures.

Cobia spawn during the early summer months. Growth is rapid. Some fish reach 20 inches before their first birthday. By age two, the average size is about 35 inches, although some fish are up to 44 inches long. Most fish caught by fishermen are between 2 and 5 years old, although cobia can live 11 years. Females grow faster and larger than males. Research indicates that of fish over 40 inches long, 85% are females.

Extended research conducted through the Gulf Coast Research Laboratory in Mississippi has shown that cobia are travelers. Under this research program, well over 10,000 cobia have been tagged Gulfwide and released. The greatest distance traveled by any tagged cobia was estimated at 1,300 nautical miles. This fish was tagged off of the Chandeleur Islands on eastern Louisiana and recaptured 1,046 days later off Hardeeville, South Carolina.

Two other cobia each traveled more than 1,200 miles. One was tagged off of Pensacola Beach and recaptured at Murrells Inlet, South Carolina. The other traveled from South Marsh Island, Louisiana to Daytona Beach, Florida in only 238 days. The all-time speed record is held by a fish tagged at Port Canaveral, Florida and recaptured 700 miles and 46 days later off Aplachee Bay, Florida. The fish averaged moving more than 15 miles per day.

Overall, 81% of the recaptures in the northern Gulf were originally tagged in the northern Gulf and 57% of the south Florida recaptures were tagged there. Research seems to indicate that most cobia likely migrate in spring from south Florida waters where they have spent the winter. Movement is northward along the Florida Gulf Coast, then westward along Alabama toward Mississippi and Louisiana. A reverse migration probably takes place in the fall, although little data on the route exists.

The data does show that not all cobia migrate, as 21 winter recaptures have been made in the northern Gulf, most at depths of more than 100 feet. None of these fish had been tagged in south Florida. Some fish may stay in the northern Gulf year-round. It is also known that some cobia stay in south Florida waters year-round and do not migrate.

This program has also provided strong clues that cobia have the ability to “home in” on exact locations. Thirty fish have been recovered at the exact site that they were tagged at 1 to 3 years earlier. It is very unlikely that they over wintered at these sites, as they were in shallow water (60 feet deep or less) where winter water temperatures can drop dramatically. More than 242 cobia were recaptured in the same general area as they were tagged in.