Parablennius pilicornis is a common marine fish widely distributed in the Brazilian coast, and it is characteristic to be the first invertebrate to colonize the artificial substratum. This specie shows many aspects suitable for its use in toxicological tests, such as: resistance to laboratory conditions, adequate size, high reproductive activity, demersal eggs, and occurence along the year in the environment. This paper presents the first results about the aspects of reproduction, embryolarval development and toxicological tests with a reference toxicant. During 6 mouths, 8 couples of P. pilicornis were maintained in laboratory conditions, feeded with frozen Artemia sp adults, partial water renovation and monitored for the occurence bearing on empty oysters shell. A total of the 38 bearing were observed with an average eclosion succes of 72 %. The average number of eggs per bearing were 137.2, where eggs development time ranged between 8 and 20 days and was function of the incubation temperature (25 to 18° C). The development stages of the embryos and hatchlings were described by following a bearing. Semi-static toxicological tests for embryo-larval stage, with the reference toxicant chloroacetamide, showed an IC25 threshold of 25 and 20 ml/l at 22 and 25° C respectively, for 15 days of the time exposure.