While it is winter here, it is the hottest part of the summer in Australia, and drought combined with high temperatures is killing thousands of fish in the NSW rivers. What is actually killing the fish?
If you said low Oxygen in the water, you are only partially right! A fish requires 5 to 6 times more Dissolved Oxygen (DO) when the water temperature is 24 degrees C (75 degrees F) as compared to when the water temperature is 4 degrees C (39 degrees F). Fish don't thrive when the DO is low - see below.
Meanwhile, the amount of oxygen that the water can hold DECREASES when the water temperature rises - see below.
So - the combination of higher demand for Oxygen plus the lower supply of oxygen is a very efficient killer of fish! This is why it's critical to run aeration devices 24 hours a day when it's warm out, and to always make sure that ponds have a sufficient O2 supply!