During a power outage, koi can survive for up to a few days, depending on the conditions. A well-maintained pond with adequate oxygen levels can support koi for about 48 hours without power. If the temperature is mild, they might survive longer. However, if the temperature drops or rises drastically, their survival time may decrease significantly. It is crucial to monitor the water temperature and try to maintain it as close to their ideal range as possible. Adding an aerator or a backup generator can also help provide sufficient oxygen to the water during a power outage, increasing the chances of the koi's survival. Additionally, reducing stress on the fish by minimizing handling and disturbances can further improve their chances of endurance during a power outage. Regular maintenance and preparedness are vital for ensuring the well-being of koi in such situations.