Diaphus fragilis

Common Name

Fragile Lanternfish

Year Described

Tåning, 1928


Dorsal Fin: 17-19
Anal Fin: 17-18
Pelvic Fin: 8
Pectoral Fin: 11-13
Gill Rakers: 17-19
Lateral Line: 36-37

Body Photophores
PVO: 2 (first at base of pectoral fin; two PVO in almost straight line with first PO)
PO: 5 (first well separated from rest; 2-3-5 in straight line; fourth elevated above level of others about at level of pectoral fin base)
VO: 5 (first, second, and third in an ascending line; third almost directly above fourth; first, fourth and fifth in straight line)
SAO: 3 (first over anus at similar level as VO5; in steep curved line; third right below LL well separated from first two almost on LL)
AOa: 6-7 (first elevated over second; last elevated slightly; rest in line)
AOp: 4-6 (almost a straight line, first before, on, or after last anal fin ray)
Prc: 4 (curving line with the fourth separated more than the other three; fourth 1.5-3 times diameter under LL)
PLO: 1 (closer to lateral line than pectoral fin, directly over second PVO)
VLO: 1 (much closer to LL than pelvic fin base)
Pol: 1 (right under LL; slightly posterior to last AOa)

Body photophores relatively small. A large triangular luminous scale adjacent to PLO is 3 times its size.

Head Photophores
Dn: present on the antero-dorsal part of orbit above nostril; large (equal to 1.5 times size of nasal organ), oval, and anteriorly directed.
Vn: present on the anterior and antero-ventral part of the orbit; elongate and thin, running from around Dn to the ventral part of the orbit, including the rear margin of the nasal organ. Mature adults with similar sized organs. A dark band of tissue surrounds the organ.
Ant present; triangular. Absent in juveniles; becomes larger with age.
Op: 2 (first small behind jaw, second above it is similar in size to a body photophore)


Body black with paler photophores. Naked skin pale. Dark tissue surrounds the Dn and most of the Vn.


Mature adults from 65-80mm.


Oceanic. Vertical migrator: found at 520-600m by day and at 15-125m at night.

Range Map

 Range Map


Tropical Atlantic: most records from S. Florida, the SE Gulf of Mexico, the Caribbean Sea, and the adjacent Atlantic around the Caribbean islands. Vagrants into the Central Atlantic and the Gulf Stream.


Hartel, K.E. and J.E. Craddock. 2003. Myctophiformes. pp. 942-951. In: FAO Species Identification Guide to Fishes of the Western Atlantic. (ed. Carpenter, K.), pp. 1308–1369. UN FAO Publishers, Rome.

Nafpaktitis, B.G. 1968. Taxonomy and distribution of the lanternfishes, genera Lobianchia and Diaphus, in the North Atlantic. Dana Report No. 73: 1-131, Pls. 1-2.

Nafpaktitis, B.G. 1977. Family Myctophidae. In: Fishes of the western North Atlantic. Sears Foundation for Marine Research. Part 7, No. 1: 13-258.