In this work was investigated the environmental toxicity of 3 new biocides(MT 200, 73532, 73503- NALCO super ( registered)) potentially effective against adult organisms of the bivalve Brachidontes pharaonis(Fischer P., 1870), an exotic species introduced in Mediterranean Sea by maritime transports(ballast water), that, recently, showed an invasive behaviour in a industrial plant in Sicily(Italy). These biocides were tested to verify their environmental compatibility at the discharge using as model organism the crustacean belonging to the genus Artemia(Leach, 1819) according to D. Lgs 152/06. Biocides were also tested using alternative crustaceans, Amphibalanus amphitrite(Darwin, 1854) and Tigriopus fulvus(Fischer, 1860), in order to check if their implementation in the National regulation as model species could affect the discharge threshold limits due to their different sensitivity, thus causing possible …