An apparatus for reducing parasite infestation of an aquatic animal, for improving the condition, appearance, meat quality or growth rate of an aquatic animal is provided. The apparatus comprises means for providing bubbles in a liquid on or near the surface of the animal or parasite and means for exposing the bubbles to sound waves, wherein the sound waves induce resonance and asymmetric collapse of the bubbles. A method of reducing parasite infestation on an aquatic animal, a method for improving the condition, appearance, meat quality or growth rate of an aquatic animal, and a method for delivery of molecules to an aquatic animal are also provided.
