The utility of cyanobacterial bloom is often hindered by concerns about the toxin content. Over three years of investigation, we found that the toxin content of cyanobacterial bloom in Lake Taihu was always low in June and higher in late summer and autumn. The findings enabled us to compare the effects of diets containing low and high toxic cyanobacterial blooms on the growth and consumption safety of tilapia. There were no negative effects on the growth of tilapia, and the muscle seemed to be safe for human consumption in the treatment of 18.5% low toxic cyanobacterial bloom. Therefore, limitations of the utilization of cyanobacterial biomass can be overcome by selecting low toxic cyanobacterial bloom that can be found and collected in large lakes.