Decabromodiphenyl ether(BDE209)is the primary component in a commonly used flame retardant.Previous studies had proved that BDE209 itself was not toxic,while its metabolites including dehrominated diphenyl ethers(De-BDEs)and methoxylated brominated diphenyl ethers(MeO-BDEs)posed a potential threat to organisms.Many studies had indicated that BDE209 could metabolize quickly in mammals,but lacking in the basic data about the metabolism of BDE209 in fish.In the present study,two replicate treatment groups of rainbow trout(Oncorhynchus mykiss)were exposed to BDE209 via a single intraperitoneal injection approximately 100 and 500 ng/g,respectively.Muscle,liver and blood samples were collected to analyze the specific metabolites on day 1 and day 28 post injection.The highest concentration of BDE209 was detected in muscle tissues,from 796.1 ng/g wet weight(day l)to 687.1 ng/g wet weight(day 28)in high dose group,suggesting that BDE209 could accumulate slightly in muscle tissues.However,BDE209 was not detected in the blood for all treatments.Most congeners of De-BDEs were found in muscle and liver tissues,with the highest concentration in the liver.The main De-BDEs were nona-,octa-,hepta-and penta-De-BDEs.A total of seven MeO-BDE metabolites were observed among different fish tissues.Blood had the highest contribution of the MeO-BDE metabolites.Each MeO-BDE congener increased over the 28 days.These results in contrast to other studies suggested possible species-specific differences in metabolic abilities.