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Five Myths about Koi

By March 10, 2011October 28th, 2021Fish

There are actually several related myths about the challenges of keeping koi. Yet, as thousands of pond owners can attest, Koi add an extremely enjoyable aspect to pond ownership. Koi are highly social fish, often compared to dogs in their desire to connect with humans. Many pond owners consider the koi in their ponds as important as their other household pets, giving them individual names and thoroughly enjoying the personal interaction with these intelligent, charming and highly social pets.

Koi myth no. 1: Your pond must be at least three feet deep to keep koi

There are thousands of two-foot deep ponds full of happy and healthy koi. A common myth is that ponds need to be deep, especially if located in a colder climate. The water in a two-foot pond will generally only freeze eight inches down, even in the coldest of climates, because of the insulating qualities of the earth surrounding the pond.

A pond that’s too deep could be considered a swimming pool by your local government and therefore fall under strict guidelines and codes. Also, more digging means more work, more water to fill the pond, and more additives to treat algae and fish illnesses.

Koi myth no. 2: Koi can’t be kept in a pond that contains plants

In a naturally balanced ecosystem, koi and plants complement and need one another. In nature, fish feed on plants. As a result, the fish produce waste, which is broken down by aerobic bacteria on the bottom of your pond, which, in turn, is used as fertilizer by the plants to grow and produce more natural fish food. It’s known as the ‘circle of life,’ and to imply that koi and plants shouldn’t co-exist is to ignore nature.

On the contrary, fish naturally love to eat plants, and most of the time they’ll survive nicely without you feeding them at all, due to plants and algae. Of course, you do need to have sufficient volume of plants in your pond to accommodate the koi. In the naturally balanced pond, proportionality is always a key ingredient to success.

Koi myth no. 3: You must bring your fish inside for the winter

Here in southern BC this isn’t a problem at all, but it’s rarely an issue even in the rest of Canada. Fish do fine during the coldest of winters as long as you give them two feet of water to swim in, oxygenate the water, and keep a hole in the ice with a bubbler, allowing the naturally produced gasses to escape from under the ice. Aside from that, you can just let nature do the rest. The fish will spend the entire winter hibernating at the bottom of the pond and then they’ll slowly wake up as the water warms in the spring.

Koi myth no. 4: You can’t have koi in a pond with rocks and gravel

Koi are actually just a fancy variety of carp, and all carp are bottom feeders. They love to swim along the bottom and scavenge everything that’s available on and in between the rocks. In nature, it’s not uncommon to find ponds, lakes, or rivers with rocks on the bottom. It’s more like their natural environment than finding an exposed rubber liner, so why even think about doing battle with nature?

Koi myth no. 5: You can’t be a koi hobbyist and a water gardener

Not true! You can raise koi and have a beautiful water garden. There are koi hobbyists who have perfectly balanced pond ecosystems with no chemicals, no sterilization, and a nice assortment of plants. The koi can grow up to be just as beautiful and just as healthy as they are in traditional koi ponds. And you’ll love them just as much!