It may come as a surprise to learn that fish need oxygen too. Without it they, just like you and I, would die. Pond aeration, or in other words, using an aerator, is one of the best things you can do for a pond and for fish.
A pond aeration system is normally an after-thought for people who own ponds. Maybe this is because we assume that water doesn’t hold much oxygen or that fish don’t need it, but nothing could be further from the truth.