NOVELTY - Nano-bio filler comprises adsorption carrier particles, which is impregnated in effective microorganisms (EM) rejuvenation solution comprising EM stock solution, molasses and deionized water, mixing, sealing and fermenting. The adsorption carrier particle is obtained by mixing composite nano powder, kaolin powder and heat-activated modified bentonite and compressing, where the heat activated modified bentonite is prepared by modifying original bentonite with sodium diethyldithiocarbamate, and nano-alumina composite powder, nano titanium dioxide and nano silicon dioxide, heating and sintering.    USE - The nano-bio filler useful in biofilters for purification of aquaculture waste water (claimed) to remove ammonia nitrogen, phosphorus and heavy metal ions.    ADVANTAGE - The nano-bio-filler: has large pore volume; has high absorption amount, specific surface area and stability; and can quickly remove ammonia nitrogen, phosphorus and heavy metal ions in aquaculture water.    DETAILED DESCRIPTION - Nano-bio filler comprises adsorption carrier particles, which is impregnated in effective microorganisms (EM) rejuvenation solution, where the nano-bio filler has a pore volume of 0.1-2 ml/g, absorption amount of 550-650 mg/g, specific surface area of 600-1300 m2/g and strong stability. The EM rejuvenation solution comprises EM stock solution, molasses and deionized water in a ratio of 5%:5%:90%, mixing, sealing and fermenting at 37 degrees C for 7-8 days. The adsorption carrier particle is obtained by mixing composite nano powder, kaolin powder and heat-activated modified bentonite in a mass ratio of 25-30%:30-40%:30-45%, compressing to a particle having a diameter of 10 mm, where the heat activated modified bentonite is prepared by modifying original bentonite with sodium diethyldithiocarbamate, and nano-alumina composite powder, nano titanium dioxide and nano silicon dioxide in a ratio of 1-5 g:10-20 g:0.5-1 g, heating to 500-600 degrees C, insulating for 12-24 hours and sintering the product. An INDEPENDENT CLAIM is also included for preparing the bio-filler, comprising (a) uniformly mixing nano-alumina composite powder, nano titanium dioxide and nano silicon dioxide in a ratio of 1-5 g:10-20 g:0.5-1 g in a furnace, heating to 500-600 degrees C, maintaining constant temperature for 12-24 hours to obtain a composite nano powder, (b) preparing heat activated modified bentonite by sodium diethyldithiocarbamate modification, (c) sodium diethyldithiocarbamate composite nano powder, kaolin powder, activated modified bentonite in a mass ratio of 25-30%:30-40%:30-45%, and compressing to a diameter of 10 mm to obtain a carrier, (d) mixing EM stock solution, molasses and deionized water in a volume ratio of 5%:5%:90%, mixing EM rejuvenation liquid, fermenting under sealed conditions for 7-8 days in an incubator at 37 degrees C, and (e) adding the carrier into the fermented EM rejuvenation liquid, culturing for 3 days, taking out and placing at room temperature for 2 days.