An experimental investigation of the removal of suspended matter from an aqueous solution was carried out with a foam separation batch system using fish mucus as the chemical. Flounder and eel mucus showed a high foaming capacity. The capacity was influenced by changes in pH and by the presence of salts in the solution. The capacity of eel mucus was weaken in the weak acidic solution (pH 5), and was enhanced in the alkaline solution (pH 10). The capacity of both types of mucus were elevated with addition of NaCl. The capacity of flounder mucus was extremely high in seawater, and the height of foaming layer was 7 times higher than in distilled water at the same concentration. When the flounder mucus was added to the bubbling solution (above 3mg · l^-1), the suspended kaolin particles were adsorbed on the foam layer and were removed from the seawater by separation. The removal efficiency was 99%. The eel mucus also removed the kaolin in the presence of salts. Foam separation is a suitable method for removing suspended matter from fish rearing water that contains fish mucus.