A small protein skimmer for aquiculture includes a sealed body, a liquid-gas mixed pump motor, a protein foam collection device and a suspensory support. The sealed body is divided into foam generated grooves and flow gathered grooves by partitions, and the generated grooves connect with the flow gathered grooves at ends thereof. The liquid-gas mixed pump motor is mounted on bottoms of the foam generated grooves for pumping water and forming a liquid-gas mixed water flow in the foam generated grooves. The foam generated grooves define apertures in tops thereof which a protein foam collection device can insert into. A flow gathered groove defines a water outlet in a forward sidewall near a top thereof and an adjusting sluice on the water outlet for adjusting water output.