Overwintering Fish in a Large, Deep Pond: Zone Considerations and Aeration

Your Pond Is Excellent

20 x 15 ft with a 6 ft deep end is ideal for wintering koi, goldfish, shubunkins, and feeders in most US zones (Zone 5 and warmer). The deep end provides a stable thermal refuge.

Critical Winter Tasks

• Maintain an Ice Hole: De-icer, aerator, or pump running at surface.
• Aeration: Air stone in the deep end (not at the very bottom to avoid supercooling).
• Stop Feeding: Below 50°F.
• Fantails: More cold-sensitive. Monitor closely. In harsh zones (5 or colder), consider moving them indoors.

Resources

Detailed guide at fishpondinfo.com/winter.htm.