Abstract: In line with the ecological engineering principle,such a link addition measure was adopted as raising loaches and paddy eels in lotus fields to form a symbiosis, which benefited both sides in increasing profit and decreasing cost of plant production.Besides the symbiosis could also effectively control lotus root eating Donacia provosti Fairmaire without the aid of pesticides, thus improving both the yields of lotus roots and fish and the eco environment of the lotus fields. Experiments demonstrated that the raising of loaches and eels in mixture yielded more significant effect with the insect control rate and yield increase rate being 83%～99% and 12.7%, respectively,than the raising of loaches or eels alone did being 66%～90% or 59%～85% and 7.6% or 2.3%, respectively.

Key words: fish lotus symbiosis, Donacia provosti Fairmaire, biological control, ecological engineering, lotus root