People are not the only ones suffering from the current hot and humid weather; it seems goldfish are feeling the heat as well.
Experts warn hot still nights can lead to fish that are kept in ponds and tanks dying from a lack of oxygen.
Those people who keep fish as pets should be aware that fish ponds and tanks can often become severely de-oxygenated at night, unless there is water movement caused by wind or a water aerator, such as a fountain or “bubbler”.
A little known fact is that tank aeration devices do not oxygenate water so much by bubbles and splashing, as by setting up currents which turn over the surface layers. Oxygen is absorbed by diffusion across the air/water interface, of which the largest is the pond surface itself.
During the day algae in water produce oxygen but at night-time, they consume oxygen. So, movement is important to keep oxygen in the water.
It is very important for fish owners to ensure the ‘bubbler’ or aeration fountain is left switched on during a hot night to ensure the tank has proper water movement.
Story courtesy of http://freshwater-aquariums.net