Last week the edges of the large koi pond were frozen, the result of prolonged cold. There is no harm that comes from this, even if the pump is turned off and the pond’s surface freezes over. On smaller ponds water must be kept moving, or a hole kept open for harmful gasses resulting from decaying leaves to escape. This pond is nearly 25,000 gallons, and there is little chance of harm to the fish unless the pond is frozen for a considerable period. Still, I keep the waterfall running through the winter.
After a few days of abnormally warm temperatures the koi (and a few goldfish) have perked up to greet me as I walk close. I’ve no doubt they are looking for food, but that will wait until water temperatures warm up in March. With cold weather forecast there is danger that the food would not digest quickly, which could be harmful.
I haven’t a clue how many fish are in the pond. Nine small koi were initially placed in the pond, but soon only three remained. But, within weeks newcomers were seen, and each year there are more little guys than my wife and I can count. At some point the number could become a problem, but for now the pond is sufficiently large to support the crowd.
Through late summer and autumn a heron frequently perched at the pond’s edge, but the deep pond made fishing difficult. If the heron caught anything, I’m not aware, though the koi were very cautious about coming to the surface for a few months. Several years ago a heron decimated the fish population of one of the garden’s smaller ponds, but the few remaining goldfish were transported to the large pond, and for now this is the only pond with fish.
The ponds and koi are one of the great joys of this garden. There are five ponds of varying sizes with the smallest less than a hundred square feet and the largest somewhere around twelve hundred. Other than a thorough cleaning in early spring, maintenance on the ponds is negligible, and in any case, certainly less than the time required to weed and mow.