- Although the flesh of the almaco jack is considered quality table fare, the species has been associated with ciguatera poisoning, a seldom fatal stomach irritation.
- The almaco jack is susceptible to tapeworm parasites in the caudal peduncle area, but the meat can be eaten safely if affected portions are cut away.
Gag have elongated but compressed bodies typical of all grouper and sea bass. Coloration is brown-gray to olive-gray with dark, irregular wavy markings on the side. The skin has a marbled quality to it, and the color of the gag deepens to dark brown after removal from the water. The anal, pelvic and tail fins are black with blue or white edges. The mouth is moderately large and the connected dorsal fins cover most of the back. Gag are often confused with black grouper but can be distinguished by differences in the tail: the back of the gags tail is slightly concave while the back of the black groupers tail is flat.
The main component of the gags diet is fish, especially sardines, porgies, grunts and snappers. They also eat crustaceans such as crabs and shrimp, as well as squid. Gag are mainly ambush hunters that rush out of crevices and caves when prey swim by.
Gag are found in the western Atlantic from North Carolina to the Yucatan Peninsula, Mexico. Occasionally, juveniles will be found as far north as Massachusetts and as far south as Brazil.
In general, adult gag are an offshore species that occupy coral reefs, rocky bottoms and wrecks in waters from 60 to 300 feet deep. However, they can sometimes be found inshore over rocky or grassy bottoms. They are the most common grouper species on the rocky ledges along the eastern Gulf of Mexico. Juvenile gag are found inshore, often in sea grass beds. Adults are mostly solitary but can also be found in groups up to 50 individuals.
- The generic name black grouper is applied to at least three different species of grouper, with the gag possibly being the species incorrectly given that name most often.