The effect of dietary intake of Coriolus versicolor Polysaccharides (CVP) on the hematological and biochemical indices of Allogynogenetic crucian carp (Carassius auratus gibelio) was investigated. Fish were fed CVP supplemented diets (0, 0.25, 0.5, 1.0, 2.0 or 4.0 g CVP kg(-1)) for 56 days. The RBC, WBC counts, hemoglobin content, ESR in blood and TP, ALT, AST, ALP, GLU, CHO, TG, and BUN in serum were measured on day 0, 14, 28, 42, and 56. After feeding of 56 days, fish were infected with Aeromonas hydrophila and mortalities were recorded. The results indicated that feeding crucian carp with suitable dose of CVP enhanced the RBC, WBC counts, hemoglobin and TP content, ALP activity, and decreased the ESR, ALT, AST, GLU, CHO, TG and BUN. There was no effect in fish at low dose (0.25 g kg(-1)). Unexpectedly, the higher CVP dose used here (2.0 and 4.0 g kg(-1)) has a negative effect in fish. The results of challenge experiment indicated that a moderate level of CVP in the diet (1.0 g kg(-1)) was the most effective to enhance the survival of fish after infected with A. hydrophila. In summary, the use of CVP, as dietary supplements, can improve the innate defense of crucian carp providing resistance to pathogens.