How to Keep Your Aquarium Cool in an Australian Summer
By Melbourne Tropical Team · 2 min read
Australian summers can push aquarium temperatures dangerously high. Here are safe, practical ways to cool your tank and protect your fish in a heatwave.
Why heat is dangerous
Warm water holds less oxygen, while fish need more when they are warm - a dangerous combination. Most tropical fish are fine up to about 28°C, but sustained temperatures above 30°C cause stress, gasping at the surface, and can be fatal. Heatwaves are one of the biggest summer risks for Australian fishkeepers.
Quick ways to cool a tank
Increase surface agitation and aeration - point a filter outlet at the surface or add an air stone to boost oxygen and evaporative cooling. Run a fan across the water surface; evaporation can drop the temperature by a couple of degrees. Float frozen water bottles (clean, sealed) in the tank for short-term relief in a heatwave - never add ice directly. Lift the lid slightly and turn the aquarium lights off during the hottest part of the day.
Bigger-picture fixes
Keep the tank out of direct sunlight and away from west-facing windows. Use air-conditioning in the room if you have it. For ongoing problems, an aquarium chiller is the reliable (if expensive) solution. A larger tank also heats up more slowly, giving you more time to react.
During a heatwave
Top up evaporated water with dechlorinated water (evaporation raises the concentration of everything left behind), don't overfeed (warm fish digest oddly and waste pollutes faster), and watch for surface gasping - a clear sign of low oxygen that needs immediate aeration.