Experimental recovery from anemia in Japanese flounder challenged with themonogenean Neoheterobothrium hirame

For clarification of the etiological agent of the anemia recently prevailin g in wild and cultured populations of the Japanese flounder Paralichthys ol ivaceus, flounder were challenged with the monogenean Neoheterobothrium hir ame. In the challenged flounder, the hematological characteristics similar to those in the recent anemia were induced. Moreover, when N. hirame were a rtificially removed from the anemic flounder produced by the challenge, the hematological conditions recovered to normal levels. These results suggest that the parasite itself can induce anemia in Japanese flounder and refute a possibility that the parasite acts as a vector of other pathogens. They also indicate that the removal of N. hirame from anemic flounder is effecti ve as a treatment of the anemia.