Epigenetic context in the life history traits of the round goby, Neogobius melanostomus

The round goby, Neogobius melanostomus (Pallas), is a typical representative of gobiids, a distinct family within the order Perciformes (Nelson 1994). Most species in this family have their pelvic fins fused into a suction disk with weak adhesion, the external lateral line being usually absent. The subfamily Gobionellinae, which includes the round goby, is mostly confined to the Caspian, Black, and Azov seas (Nelson 1994). Members of this subfamily are primarily benthic and therefore do not have a swim bladder (Nikolsky 1954). Neogobius melanostomus is a small, soft-bodied fish. Its head width is about equal to its depth; the snout is oblique and convex in profile. The anterior and middle nape, upper opercule, breast, pectoral fin lobes, and part of abdomen are covered with cycloid scales, the rest of body with weak ctenoid scales. The dorsal fins are contiguous. The second dorsal fin is uniform in height, while the first dorsal fin has a prominent posterior black spot (Berg 1949, Miller 1986). Both sexes have an erectile urogenital papilla between the anus and the base of the anal fin, a subject of sexual dimorphism (Miller 1984).