Spring has sprung, which means our koi pond in My Big Backyard has thawed and our three koi fish are waking up. Soon, we will install their enrichment tank, which “floats” above their pond. They swim up into the tank to see you at eye level and show off their beautiful scales!

Did you know that our koi actually stay in their pond all year round? In the winter, the top several inches of their pond freezes, but the deeper water does not. During this time, the koi go into a sort of hibernation, where they don’t eat or move much. When the water thaws and the temperatures start to rise, they start to perk up and look for food. We give them a very bland and minimal diet at first (usually a few plain cheerios) to help restart their digestive systems. After a few weeks, they are ready for their higher-calorie and protein diet!

Our three koi all have names and are easy to tell apart. Princess Peach is the largest and is mostly white with peach and black spots. It is difficult to identify the sex of the koi, so it’s possible that Princess Peach is actually a prince. Luigi is second-largest and is all silver in color. Mario is the smallest and is mostly orange with black spots. Though we do not have exact ages of the koi, we do know that Mario is at least 20 years old and the other two have been at the Zoo for 11 years.

Like nearly every animal in the Zoo, our koi participate in various training opportunities. My Big Backyard keepers have worked with them to target train, which means they know to swim to a “target stick” (a wooden pole with a ball on the end of it) for positive reinforcement. Princess Peach seems to be the most curious of the group and tends to participate more frequently than the other two. Luigi is the most cautious and prefers to observe training from afar. Our keepers do not touch the koi, as they have a protective layer of mucus all over their scales to help keep them healthy. So when you come to visit the koi, be sure to look, but please don’t touch.

The koi, like all of our other animals, also enjoy enrichment provided by their keepers. Each spring, a large fish tank is placed in their pond upside down. We then suck the air out the tank so that it fills with water. The koi get more swimming space and the opportunity to swim above their normal pond level, and it allows guests to really see their size, color, and very funny fish faces! Be sure to stop by My Big Backyard on your next Zoo visit to see Princess Peach, Luigi and Mario.

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