The invention discloses a fish, vegetable and 
shellfish symbiotic 
engineering circulating water double-layer culture tank, and belongs to the technical field of 
aquaculture equipment. The fish, vegetable and 
shellfish symbiotic 
engineering circulating water double-layer culture tank comprises a tank body, a floating 
bed, a bottom 
fish screen and other structures, the floating 
bed is located at the top of the water outlet end of the tank body and provided with a plurality of planting holes, aquatic plants are planted in the floating 
bed, the interior of the tank body is divided into two parts which are deep in the upper portion and shallow in the lower portion through the bottom 
fish screen, fishes are cultured in the upper tank body, and filter-feeding shellfishes are put in the lower tank body. Through the root systems of the aquatic plants, COD, 
nitrogen, 
phosphorus and other nutritive salts in 
aquaculture water can be effectively absorbed, 
sedimentation of suspended particulate matter in the water is promoted, meanwhile, granular 
organic matter is removed through the 
filter feeding effect of the bottom shellfishes, the problem that an existing 
aquaculture water tank is low in 
waste collection efficiency is solved, the yield of the shellfishes and the aquatic plants can be increased, and meanwhile, the landscape aesthetics value is realized.