If you notice your fish gulping at the water surface add an air stone to the water to help increase the oxygen levels in the water.
Remove any yellow or dying plant leaves and perform any general gardening maintenance.
Summer is comprised of July, August and through mid September for ponds. It is during this time that your fish will bulk up and store their fat, they will also show large growth spirts during this time. This also the second most dangerous time for fish because of high temperatures we have here.
Things to do and watch for:
Watch the water temperature. Water temperatures above 86° F can kill fish. Add floating plants, shade trees or cool water changes to keep the temperature down.
Feed your fish less frequently as the temperature gets closer to 86° F
Short stretches (a day or two) of higher temperatures will not hurt the fish though.