I made a wheel barrel pond with water hyacinth, duckweed, and mosquito fish. I checked the ph of the water and it was perfect. I live in Daytona Florida and we have a heatwave of around 90-85 degrees, I checked the water temperature and it is 75-85 degrees during the heat of the day, but down to 70 at night. I put feeder fish in the pond and each one dies a day, they slow down, hide, then die. I have to keep on picking up the plants to find them. The orange ones are dying first, I have a water bubbler to add oxygen to the water. All the fish seem lethargic and have repetitive movements. I feed them according to instructions. I properly added Amquel to the water before introducing the fish. Why are they all dying?