The smooth lumpfish (Aptocyclus ventricosus) is a species of marine ray-finned fish belonging to the familyCyclopteridae, the lumpfishes and lumpsuckers. This species is found in the northern Pacific Ocean. It is the only species in the monospecific genus Aptocyclus.
The smooth lumpfish, or smooth lumpsucker, is a deep sea fish species with a body length of 6–44 cm (2.4–17.3 in) and body weight of 0.05–4.20 kg (0.11–9.26 lb) on average.[5] They look brownish gray with dark spots dorsally, muddy gray ventrally. They have naked skin without scales and tubercles. A smooth lumpfish has no dorsal spines or anal spines, eight to nine dorsal soft rays, and seven to nine anal soft rays. They have a rounded caudal fin and large and broadly based pectoral fins. Their pelvic fins are modified to form a clinging disc with a thickened margin on the ventral surface of the body. They have their first dorsal fins completed embedded under the skin.[6]
Smooth lumpfish are widely distributed throughout the North Pacific, especially in the Aleutian Basin. They inhabit both near-bottom and mid-water layers, ranging from 5to 1,700m. They are preyed upon by certain fish species, marine mammals and seabirds.[7] Their preferred diet consists of medusa and ctenophores, and they occasionally also feed on pelagic polychaetes and crustaceans.[8]
The smooth lumpfish is an iteroparousgonochoristic species with determinate fecundity, group-synchronous ovary organization, total spawning (release of 1 batch of eggs per breeding season), and external fertilization. Smooth lumpfish perform spawning migration from deep-ocean to coastal zones, where breeding occurs over a rocky bottom at depths shallower than 10 m (33 ft). A thick envelope protects these demersal eggs from mechanical damage during development in the coastal zone. The incubation time between fertilization and hatching is more than 40days. Males protect the egg clusters after females spawn.[7]
^Orlov, A.M. & Tokranov, A.M. (2008). Specific features of distribution, some features of biology, and the dynamics of catches of smooth lumpsucker Aptocyclus ventricosus (Cyclopteridae) in waters of the Pacific Ocean off the Kuril Islands and Kamchatka. J. Ichthyol, 48: 81. https://doi.org/10.1134/S0032945208010086
^Eschmeyer, W.N., E.S. Herald and H. Hammann, 1983. A field guide to Pacific coast fishes of North America. Boston (MA, USA): Houghton Mifflin Company. xii+336 p.
^Yoshida, H., & Yamaguchi, H. (1985). Distribution and Feeding Habits of the Pelagic Smooth Lumpsucker, Aptocyclus ventricosus (Pallas), in the Aleutian Basin*. BULLETIN OF THE FACULTY OF FISHERIES HOKKAIDO UNIVERSITY, 36(4), 200-209. Retrieved February 26, 2018, from http://hdl.handle.net/2115/23891
