Overfishing is a problem because it harms the fish's eco system. If you fished of all of a little fish out of a pond, the medium fish don't have anything to eat! If you fish al the big fish out, then no one is there to eat the medium fish and they will over populate and eat all the little fish and then they wouldn't have anything to eat! If you want to help, buy farmed fish if you eat fish. Those fish were raised to be eaten. Another way you can help is when you go fishing, let the fish go after you took a picture or 2.
Hope this helps :D
