Astronesthes richardsoni chin is ribbon-like and lacks a bulb or swelling at its tip. The dorsal fin has 12 to 14 soft rays and the anal fin has 13 to 18. The origin of the dorsal fin is behind the insertion of the pelvic fins. There is a dorsal adipose fin anterior to the caudal peduncle, and a small ventral adipose fin just anterior to the anus. There are two rows of photophores (luminous spots) on each side of the underside of the fish, numerous other photophores on the head and body and a luminous patch on the edge of the preoperculum;
Notoscopelus elongatus the anal fin 18 to 19, and in the pectoral fins, 12 to 13. There is a distinctive arrangement of photophores (light-emitting organs) on the head and body. At a length of about , males develop luminous, glandular patches on the dorsal surface of the caudal peduncle. It is very similar in morphology to "Notoscopelus kroyeri" but differs in having 23 to 25 gill rakers whereas "N. kroyeri" has 26 to 29. "N. elongatus" is endemic to the Mediterranean Sea where it is found in greatest abundance in the Western Basin and the Ligurian Sea and Tyrrhenian Sea. During the