The Pond in my backyard

The pond in my backyard is located at the edge of a wooded area. Once it dried out totally due to a lack of rain and a long period of dry weather. Koi and comet fish all died and the frogs disappeared until it rained again. It filled up little by little and finally the pond water came back to its normal level. We bought 20 small fish again, and a few years later it became hundred of them. Especially after the rain, all the fish were floating on the surface. It's fun to watch. Below you can see a big bird, a heron (?) trying to harvest a fish meal.