Strong Chlorine and Bromine Chlorine Hydantoin were used as acute toxicity for fries of Ctenopharyngodon idellus.The results showed that the safety consistence of Strong Chlorine and Bromine Chlorine Hydantoin for fries of Ctenopharyngodon idellus was 0.443 6 mg·L~(-1) and 4.676 3 mg·L~(-1).The sensitivity of Strong Chlorine and Bromine Chlorine Hydantoin for fries of Ctenopharyngodon idellus is Strong: Chlorine Bromine Chlorine Hydantoin.