Not a lot is known about the reproduction patterns of sharksuckers. Spawning occurs in the warm seasons, spring and early summer in most of its range, and during the autumn in the Mediterranean. The sexes are separate, sperm and eggs develop in male and female individuals. In males, sperm passes from the testis to the outside by a specially developed duct (Lagler et al. 1962). Eggs are fertilized externally then enclosed in a hard shell, which protects them from damage and drying. The eggs can still hatch after they have been washed onto the shore, due to the protective shell that forms around them. Eggs are large, pelagic and spherical in shape. Newly-hatched E. naucrates are 4.7-7.5 mm long, have a large yolk sac, non-pigmented eyes, and an incompletely formed body. Immature fish live freely for approximately one year until they are about 3 cm in length, which is when they attach themselves to a host fish. When the newly-hatched E. naucrates are still developing, the sucking device begins forming. Also, the fish develop small teeth on the upper jaw, and large teeth on the lower jaw. The fish reach sexual maturity within three to five years (Lagler et al. 1962).