Parioglossus taeniatus Regan is a small Eleotrid goby, some 35 mm in total length. It was previously known collected from Aldabra in the Indian Ocean (T. Regan : 1912) and the Palao Islands in the Pacific Ocean (T. Abe : 1939). The author collected over one hundred specimens of this fish, containing juveniles from the coasts of Kyushu and Shikoku, Japan (Fig. 1). The fish lives a gregarious and semi-pelagic life in the middle stratum of the water of inlets, feeding on the planktonic copepods. Twenty-one mature fish, collected with a small pit-net, were kept for thirteen days in a table-aquarium. During this period, it was observed that the fish swimmed in the aquarium in day time, and at night they rested under a vacant hollow of a valve of a large shell, lying on the sand-floor of the aqarium. After they were kept some time, the ripe fish were used for artifical insemination. The spawning-season seems to extend from the beginning of July to the beginning of September in the Amakusa Islands, Kyushu. The black, nuptial coloration appeared in the anal fin of the ripe male fish. The number of ripe ovarian eggs was enumerated as from 947 to 2,4E3 according to the size of the parent fish (Table 1). The fertilized egg by artifical insemination is elipsoid in shape, 1.3 mm in long axis and 0.6 mm in short axis, demersal and adhesive, with a boundle of the adhesive filaments at its basal end. The numerous oil-globules in the yolk are grouped in some eggs, or scattered in others (Fig. 2). The incubationperiod extended about four days at the water-temperature 25～28℃. The newly hatched larva is about 2 mm in total length possessing characteristics of gobiid larvae (Fig. 3, A). The juveniles were observed to live swimming life with adults late summer on the coast of the Amakusa Islands (Fig. 3, B～D). The fish seems to grow 20～37 mm in total length in one year, some individuals becoming mature. The life-span seems to be over two years.