tilefish, common name for a superior and brilliantly colored food fish of temperate and tropical waters, marked by fleshy flaps on the top of the head and at the corners of the mouth. It is a bottom feeder reaching 3 ft (91 cm) in length and 35 lb (15.8 kg) in weight. Since it thrives only at depths of 50 to 100 fathoms (300–600 ft/91–182 m) and temperatures of about 50°F (10°C), it is thought that the curious and dramatic fluctuations in its abundance are caused by shifting currents of varying temperatures. The common Atlantic tilefish is Lopholatilus chamaeleonticeps. Tilefishes are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Perciformes, family Branchiostegidae.