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;
Apistogramma eremnopyge Apistogramma eremnopyge Apistogramma eremnopyge is a species of cichlid. It is only known from the Rio Pintuyacu, a tributary of the Rio Itaya near Iquitos, Peru. Most of the tributaries of this river system carry acid blackwater (pH ~ 5). This is a small cichlid, standard length which can be easily distinguished from its congeners by the presence of a prominent dark blotch on the lower part of the caudal peduncle in both sexes. The male is strikingly coloured with vivid blue and red patterning on the cheek and operculum and maroon, orange and blue colouring on the dorsal fin.