An investigation on the effect of application of livestock manure, the biomass of aerobic heterotrophic bacteria and Colicin population and distribution of Aeromonas, Pseudomonas and pathogenic bacteria of the human digestive tract which are also present in the body mucus of black carp, grass carp, silver carp and bighead carp as well as in pond water (on the application of manure of chicken, duck, cow and pig) was conducted in the fish farming areas in Wuxi, China.