A Fish's View of the World
Though fish live under water, their view is not restricted to seeing underwater. Many fish in fact need to be able to see insects and other animals above the water as they are sources of food or potential threats to the fish. Fish see everything above the water, distorted a little, and possibly a lot if the surface is rippled.. Their field of view is restricted by the angle at which total internal reflection takes place.
If the refractive index of water is n then the critical angleis given by
The fish can also see objects under the water, either directly or by reflection from the water surface.