Can a Koi Pond Be Too Deep?

Koi fish are fun to have. A nice pond in the backyard is always a fun, relaxing way to spend your time. Watching the fish in a cool seated are with the breeze flowing over you sounds like a perfect day.

Can a Koi Pond be too deep? No, a Koi Pond can’t be too deep. If anything, you would have to worry about the koi pond being too shallow. A Koi Pond that is too shallow would be bad for the fish that you have in it and can result in many health issues, and even death.


Koi Ponds can be fun when maintained properly. If not, there can be repercussions for the fish in it, which we’ll be exploring more in-depth.

Koi Ponds and Their Depths

How deep you want you Koi Pond to be should be based on how many fish you want and how big you want your fish to grow to be. As with all fish, they will only grow to the size of the koi’s environment, up to a point. Meaning if you put one fish in a pond, it won’t grow to be the size of a dog.

The main factors you need to consider when getting a Koi Pond are this:

  • The size and depth of the Koi Pond
  • The amount of fish you want in your Koi Pond
  • How big you want your fish in the Koi Pond to be
  • What grade of pump you are going to need for your Koi Pond

How Deep Does my Koi Pond Need to be?

Depths and size of Koi Ponds always vary between the space you have to work with. According to Hartz, “the ideal size for a Koi pond is considered to be over 1,000 gallons and at least three feet deep.” That is a lot of water to be using.

So, for a Koi Pond that is 3 feet deep and is using at least 1,000 gallons of water, you can have an average of 5 good sized fish. If you are looking to have larger fish, then this will be the best set up for you.

If you want more than 10 fish, you’ll need a pond that can accommodate over 2,300 gallons of water. For the 1,000-gallon pond, you would need roughly a 6’ x 8’ area to build it. The larger fish and more fish that you want, the larger your pond is going to need to be.

How Many Fish Should I get?

If you want a lot of fish in your pond, you’ll have to know just exactly what you want in your Koi Pond. It isn’t suggested that you put other fish in your Koi Pond along with the Koi Fish. The Koi Fish are very dominant and could eat the other fish. Even if they didn’t eat the others, they are extremely quick and would eat most of the food before the other fish could eat.

However, you can put other fish in a Koi Pond besides Koi Fish. Velda claims that other fish can be put in a koi Pond instead of Koi Fish. These fish include,

  • Algae Eaters
  • Flathead Minnows
  • Golden Rudds
  • Golden Tenches
  • Goldfishes
  • Ides
  • Pumpkinseed Fish
  • Shubunkin Fish
  • Sturgeon Fish

Depending on which fish you get, you need to remember that you have a limited amount of space for your fish. If you have too many fish, it could be too much for your pond filter to handle. A filter can only clean up to a certain amount of waste from the fish, including the waste from the plants too.

How Big will the Fish get?

Your fish can get quite large depending on their breed, how much you feed them, and how large of a pond they are in. The site Koi Acres reports that “Most domestic Koi usually grow about 12 to 15 inches long. Japanese Koi usually grow 22 to 26 inches in length. Jumbo-sized Koi grow up to 34 to 36 inches long.” The biggest Koi Fish ever recorded weighed 90 pounds! That’s huge!

Although they won’t grow as big, goldfish can also become quite large in a pond setting or the wild. Unlike in an aquarium or a tank, Goldfish have more room to grow bigger. In a tank, Goldfish only grow to about 1 to 6 inches and weigh about 1 to 4 oz. In a pond, Goldfish can grow 12 to 14 inches and weight about 0.3lb to 1lb. The largest one ever recorded was over 2lbs.

Pumpkinseed fish, or as they are more commonly known as the common sunfish, can grow big for their size as well. The average size for the pumpkinseed fish is 4 inches in length and weighs about 0.4lbs. They can grow as large ad 11 inches and weigh 1lb or more. The record for the largest pumpkinseed fish is 1lb 8oz. You could have an abundance of these fish in a pond.

Sturgeon fishes are quite an interesting breed of fish. They are also one of the oldest fish known to still be around. The date back to the Triassic period of dinosaurs and survived the extinction that ravaged our planet so long ago. They have many breeds, and some can weigh up to 2,500lbs, so make sure to get the right breed that is small enough to put in your pond.

Pumps for your Pond

One of the main things that you will need for your pond to run smoothly is going to be a water pump. For a Koi Pond, you’ll need a powerful one if you are going to be moving around 1,000 gallons of water at a time.

There are two types of pumps that you can use, submersible ones and non-submersible ones. You would need a submersible one if your pond is 1,000 gallons or less. Usually, the pumps are measured by how much water they can move. Smaller pumps are measured by gallons per hour (GPH), and larger pumps are measured by horsepower (hp).

Smaller ponds will use a small pump that generally will pump 500gph if the pond is 1000 gallons. To be sure that your pump is sufficient, find one that can pump at least half the amount of water in an hour. Doing this will be sure that you can cycle all of the ponds water within 2 hours and will also make sure that the fish aren’t disturbed as well.

If you get a pump that is too powerful for your pond, you may end up sucking in smaller fish and up hurting or killing them. So, make sure your pump isn’t too strong.

Cost of Koi Ponds

On Amazon, you can find Koi Ponds that cost within the $200 to $500 range. However, the bigger the pond, the more expensive it can get. The bulk of this will be in making the size. To know how much. The more gallons of water it needs, the more of hundreds of dollars it will cost. Not to mention all the parts and labor it will be to put together.

Cost Owl says that “a DIY project… might cost $500 to $1,000” for a small pond,” “a professionally installed (small) pond might cost $2,000 to $3,500,” and “Larger ponds…can easily cost $5,000 to $15,000 or more.”

In the case of building one, it is up to you on whether or not you want to attempt a DIY project yourself. However, the quality of it may be worth the money.

On top of this cost, you will also have to factor in the price of water to your water bill, as something like this will make it spike up in terms of water use. It will be the equivalent amount of a swimming pool if not less.

Koi fish are a lovely sight to have in your backyard and can have an amazing effect on relaxation and relieving stress, but is it worth having? That question is for you to decide.


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