They are only found in the western portion of the tropical Atlantic Ocean, where they are often caught with trawling nets or by angling, and used as food.

[2] The knobbed porgy was named by John Randall and David K. Caldwell as part of a 1966 review of the genus Calamus, which was published in the academic journal Science.

[3] Knobbed porgies have a fairly deep body with a steep profile, and a nape that projects noticeably in larger adults, later developing into a humped 'forehead'.

[4] They are similar in coloration to the littlehead porgy, with silver to brass bodies with a rosy cast and violet snouts and cheeks.

[8] It is found over hard bottoms at depths from 7 to 90m, and can also be associated with ledges, coral reefs,[2] and near-by areas of gravel, grass or sand.