Adding a pond to your backyard is a great way to transform a static landscape into a dynamic oasis; put some koi into that pond, and you’ll never want to leave your backyard. But before you start the big dig, here are some points to consider.
The cost of your pond will vary depending on the size you decide to build it, the number and size of the fish, and the type of filter you decide to buy. If you’re willing to start out with smaller fish (3-6 inches) and wait a few years until they’re full size (1-3 feet depending on the variety), then you’ll save yourself hundreds of dollars on the cost of the fish. Digging out the hole yourself is another money-saver, but in all likelihood, you’ll be spending at least $2,000-$3,000 for a koi pond.
While some believe the phrase “The bigger, the better,” to be of modern origin, it’s actually an old Japanese saying about Koi ponds.
Alright, that’s not true, but many people do say that it’s better to build your pond too big than too small. So while there are many recommendations out there for a 1,000 gallon pond, you’ll want to aim for at least 2,000. Of course, you might not have that much space to work with, but that’s nothing to worry about—you can always sell your home and find a new, more accommodating piece of land.
Well, maybe not. But in all seriousness, you’ll need about six to eight feet in diameter, and a depth of at least four feet (more on that later). You can always work backwards with the number of fish you want to have, assuming 1,000 gallons is suitable for five fish.
Aside from what color fish you want to buy, selecting a filtration system is the most important decision you’ll make when installing a koi pond. Fish waste, decaying plants, and left over fish food all contribute toward the dirtying of the pond. There are many different kinds of filtration devices, ranging from simple pumps to complex systems.
It might be tempting to lean on the less expensive side—but be careful—a poor filtration system can quickly turn your koi-fueled fantasy into an algae-infested nightmare.
After all the work you’ve put into your pond, the ultimate buzzkill comes when a predator kills your fish. Constantly sitting by the pond with a shotgun in your hand will usually deter most predators from the hunt, but if you’re like most people, you have other things to do throughout the day.
Fortunately, you can still keep your fish safe if you build a deep pond. If your pond is only three feet deep, the koi’s most pesky predator—the great heron—will have no problem snatching up your koi for a quick lunch. But if you build your pond six to eight feet deep, with plants and rocks for your fish to hide under, the great heron will likely fly away still hungry.
Another precautionary step is to run fishing line across the pond, inhibiting the heron from safely landing.