How Many Koi Should You Have In Your Pond Per Gallon?

Keep Your Colorado Springs Koi And Pond Happy And Healthy By Having The Right Number Of Koi

There are 3 basic rules you can follow for finding out how many koi can fit in your pond. The difference really comes down to what kind of math you want to do and the information you know about your pond. It’s best to have a few less fish so the ones you do have stay happy and healthy.

Let’s find out how many fish can fit into a pond per gallon.

How many koi in a pond is the right amount

1 Fish, 2 Fish, 3 Fish, 4?

“Now that we have a pond you know what that means!”

Sabrina looks at Harvey, eyes bright with excitement. Harvey has no idea what she’s talking about and tells her as much.

Dog making friends with koi fish who are happy because they have enough room

Sabrina rolls her eyes, saying “Koi, Harvey, it means we can get some koi fish to swim around in our pond!” Harvey wants to know how many, exactly, Sabrina wants to put in the pond. “However many koi fit in our pond,” is her response.

Harvey shakes his head and pulls out his phone to find out how many koi fit in a pond per gallon.

How Many Koi Fit In A Pond Per Gallon

Rule #1- 6 inches of fish for every hundred gallons of water
Rule #2- 1 inch of fish per ten gallons of water (for well filtered and aerated ponds)
Rule #3- 1 inch of fish for every square foot of surface area (for a 2 foot deep pond)

You’ll want to know what kind of koi you want, whether it’s average domestic, Japanese, or jumbo. Each grows to a different size.

Correct number of koi fish swimming around in a beautiful pond

Average domestic koi can grow up to 15 inches long so it’s best to measure using that standard. This way your fish will end up more comfortable than cramped. So for measurement sake, the number you should have per gallon goes like this:

  • 100-gallons: 1 smaller fish
  • 150-gallons: 1-2 smaller fish
  • 250-gallons: 1-2 koi
  • 300-gallons: 1-2 koi
  • 500-gallons: 2-4 koi
  • 750-gallons: 3-5 koi
  • 1500-gallons: 6-10 koi
Koi fish swimming in a pond at night lit up by LED lights

Harvey goes over the math in his head real quick (he was a math major in college) and it checks out. “So how many can we get for our pond, Harvey?” asks Sabrina.

Harvey does some more math in his head and smiles, saying “3 would be a good starting point. After a while, we can add in one or two more if it seems like it’ll work out.”

1 Week Later…

Sabrina and Harvey watch the flashing scales of their fish as they lazily swim around their new home. All 3 of them seem happy and healthy and the couple plans on helping them stay that way.