Notoscopelus kroyeri dorsal fin has 21 or 22 soft rays, the anal fin has 18 to 20 soft rays and the pectoral fins have 12 to 13. Like other members of the genus, it has many small photophores on the sides and flanks of the fish, arranged in a fashion that is characteristic to this species. Mature males have a gland consisting of eight or nine luminous scale-like segments on the dorsal surface of the caudal peduncle, but they lack the bioluminescent patches on the cheek and above the eye that are characteristic of some members of the genus. "N. kroyeri" is
Operculum (fish) the shape is visible and then the individual components are developed days later. The size and shape of the operculum bone is dependent on the organism's location. For example, fresh water threespine sticklebacks form a less dense and smaller opercular series in relation to marine threespine sticklebacks. The marine threespine stickleback exhibits a larger and thicker opercular series. This provides evidence that there was an evolutionary change in the operculum bone. The thicker and more dense bone may have been favored due to selective pressures exerted from the threespine stickleback's environment. The development of the operculuar series has changed dramatically