Pond Boss Forums INTRO Questions & Observations Aeration "Supercooling"

If fish can be stressed by the supercooling of the deeper water by aeration, then how do cage culture fish fare when they are essentially trapped in a pen close (within 5 feet) to the surface, where theoretically the water is the coldest. Are there different guidelines for aeration if you're floating a cage of trout or HSB in a northern pond? Since water starts its natural migration to the surface at 39 degrees, and reaches the surface when it is at or very close to 32, the surface waters must be pretty nippy for the caged fish. Are they stressed similarly to the fish supercooled by bottom aeration over the winter?