It is 14 acres of murky water, flowering trees and evergreens.
"The construction of the garden started in 1974 and the dedication of the garden took place in 1977," explains Ben Chu, Horticulture Supervisor at the Missouri Botanical Garden.
And even back then these guys, at least some of them called the Japanese Garden home.
"A lot of these koi have been here since 1977, 1976," he goes on to say.
They don't steal the show, but they certainly entertain.
What you might not realize is they serve another purpose.
"When you have a perfectly clear water source the reflection of the landscape is not quite as distinct as when you have a cloudy situation for the landscape to be reflected in the water surface," he goes on to explain.
So these hungry creatures stir things up, but carp aren't the only fish swimming in this lake.
"We have some large mouth bass and we also have some sun fish and bluegill that are, they're a little more elusive and you can't really see them as readily as the carp."
He and his crew don't feed them, they don't need to.
"Oh no, no, we don't feed them I think they get plenty of food through the course of the day by visitors," Chu says.
However, they do refill the fish food dispensers twice a day.
"It's somewhere around 200 pounds a month that we'll bring in and put into the fish food dispensers."
And that keeps them at a pretty hefty weight.
"35, 40 pounds would probably be some of the larger fish," he says.
So the Koi might not be the main attraction in the Japanese Garden, but they do make it an even more colorful place.