Water hyacinth is a deadly weed in an aquatic environment but a potential feedstock for the generation of renewable biogas through anaerobic digestion. Biochemical methane potential (BMP) was examined for fresh water hyacinth whole plant after microbial pretreatment to determine the ideal food to microorganism (F/M) ratio. The study revealed that after microbial pretreatment of water hyacinth the F/M ratio 1.5 showed the highest methane yield of 156 +/- 19 mL CH4/g VS on the 20th day. It was observed that the microbial pretreated water hyacinth illustrated enhanced biogas production within a short time period when compared to the untreated water hyacinth. The ideal F/M ratio played a significant role alongwith the microbial pretreatment process to accelerate the hydrolysis period and increasing biogas generation.