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;
Caudal cell mass dysraphisms. These types of abnormalities arise from specific structures formed in the caudal mass, for example if proper differentiation of the caudal mass doesn't occur, it could result in a type of spinal dysraphism. One example of spinal dysraphism is caudal regression syndrome. Patients suffering from caudal regression syndrome can experience a varying degree of the abnormality ranging from partial lack of the tail bone and pelvis to more significant cases where there may be paralysis and, as a result, inhibited function in the bowel and bladder. This abnormality can be caused by the caudal cell mass not developing properly