If you have tropical fish you need a 36-72 hour Emergency Tropical Fish Tank Heater. They only cost about a $1 to make (without the height adapter seen on the right). Use multiple Emergency Heaters for larger fish tanks. Keep a few ready for the next power outage.

One Emergency Heater will last approximately 36 hours running non-stop. It's designed for a minimum tank size of 1 gallon running only 50% of the time, up to multiple heaters running 100% of the time. Keeping any size fish tank's water around 80 degrees is possible during power loss with the correct number of heaters per gallon. Emergency Heaters will work with fish tanks 7" or taller.