When it is cold outside, we often need to net just one fish out of the water and no matter how hard we try we can't do it. We often end up cold and wet and covered with pond scum because we tried so hard to reach just a little bit farther. Why on earth would we need to know how to get fish out of the pond? Sometimes fish have some sort of disease and treating the entire pond is almost impossible, but treating a few sick fish is economically feasible.
Pour warm water into one end of the pond. The fish will come toward the warm water and right into the net you have conveniently placed there.