Biological techniques by aquatic macroanimals to improve water quality may be classified overally as three types. The fist is to use aquatic palnts for nutrient removal, the second is to use grass fish to control algae or aquatic plant, and the third is to modify trophostructure by using top-consumer to control algae(top-down effect). This paper includes a general review on above-mentioned techniques, some experimental or field-based results, and some discussion on Korean status and prospect on this part.