Indoor Koi Pond

Keeping Fish Indoors Has Many Benefits

Koi ponds aren’t limited to the outdoors. I have an indoor koi pond, and my kids don’t use it for wading or sport fishing. My koi fish thrive inside my house, and the pond is amazingly easy and convenient to clean.

Anyone thinking about an indoor koi pond will want to keep reading. I’ll fill you in on everything from indoor koi pond designs to how to change the water without making a mess.

Benefits of Indoor Koi 

The American Association for the Advancement of Science released a study in 2019 detailing the psychological benefits associated with regular exposure to water features.

An Indoor Koi Pond for Commercial Use
A Photo of an Indoor Koi Pond

Reducing stress and improving our mental well-being are benefits everyone can appreciate. I know I find watching my koi lazily swim around the pond always relaxes me. While stress relief is great, it’s not the only benefit indoor koi ponds can provide.

Enhance An Indoor Space 

I was surprised to learn I increased the overall value of my home by adding a koi pond. I have a large entryway area, and my pond’s design is customized to highlight some of the space’s features.

By adding lighting elements, I created a specific mood. I also decided to add some unique features to the pond. With multiple materials to choose from, like stone, wood, and cement, designing a koi pond that enhances any indoor space is easy.

Adding rock shelves is another way I customized my pond, and it also creates new places for my fish to explore.

Easily Create a Safe Environment for the Fish 

Keeping koi fish outside in a backyard pond comes with a lot of potential problems, primarily hungry predators. Birds, neighborhood cats, and other critters all think koi make a delicious treat. Covering the koi pond is a solution, but it’s not always effective. It also spoils the look of the pond when you have a wire covering over the top.

A Photo of a White Koi With Orang markings Swimming in an Indoor Koi Pond
You Can Create a Specific Mood for Your Koi Pond

Indoor koi don’t need the same protective measure, even when there’s a cat in the house.

Another advantage of having a koi pond in the house is never worrying about the weather’s effect on the fish. It’s easy to create a consistent climate the fish will thrive in.

Convenient Monitoring 

One thing I noticed with my koi pond indoors is I pay more attention to the fish. Since I’m spending more time watching the koi swim in the water, I’m more likely to notice when something is wrong.

Being able to catch a problem before it affects all of my fish is better for their health. It’s also easier on my wallet. I’m not replacing sick koi with healthy ones as frequently.

Considerations Before Installing an Indoor Koi Pond 

There are benefits to indoor koi ponds, but it only applies after considering the following. The climate inside your home matters, along with the available space. It’s also a good idea to think about any kids and pets. I recently discovered my dog happily drinking the pond water.

A Group of Koi Swimming in a Pond
Always Check on the Humidity of Your Koi Pond


Indoor koi ponds produce some humidity. Warmer water temperatures are necessary for the fish’s survival, but it can make the atmosphere in the home a little uncomfortable.

To get rid of the heat and moisture in the air from the pond, a ceiling fan or dehumidifier might be necessary. It’s an added expense, but worth it to keep a healthy koi pond inside.

Keeping the Water Clean 

With the right filtration system, it’s possible to reduce how often the water needs to be changed. Look for mechanical and biological filters. Certain plants will help keep pH levels balanced, along with automated systems.

It’s easy to find the right balance between the filters to keep the water clean with minimal fish waste, pH levels balanced, and the indoor pond looking great.

A Beautiful Koi Pond With Different Colored Flowers and Koi Swimming in the Background
An Indoor Koi Pond Keeps Your Koi Safe From Predators

Adequate Lighting 

Not all homes have enough natural light for indoor koi fish to thrive. Adding windows and skylights is an option, but it’s expensive and messy. A better option is to have lighting installed in or around the pond.

Look for UVA or UVB bulbs. It will provide the light necessary to grow healthy algae and water plants while also helping to minimize chemical build-up in the water.

Watch Out for Any Indoor Pond Leaks 

The indoor pond contains water. It’s not enough to flood a home, but cleaning up a leaky koi pond is not fun. Even though it comes with a pond liner, it doesn’t ensure there won’t be an eventual leak. Keeping an eye on the indoor pond is mandatory. Check it every day. It’s surprising how quickly a small leak can spring up. If you ignore it, it will get worse.

A Bunch of Colored Koi Fish With Different Patterns and Markings
Have Adequate Lighting Around Your Koi Pond

Make Sure There’s Space for the Koi Pond 

If you have plenty of room for a large indoor koi pond, you can skip this section. I have a smaller home, so space is something I needed to consider.

Crowding koi in a small pond isn’t healthy for the fish. It leads to illness and makes it challenging to keep the water clean.

Weight and size are other considerations. Water is heavy. One gallon of water weighs around 8.4 pounds. Imagine how much weight the pond puts on the floor. Finding out the weight limit for the flooring is crucial. No one wants their koi pond crashing through the floor.

Remodeled basements and the ground floor level are the best places for a koi pond indoors. Look for a supporting wall or column. It provides additional support for the pond’s hefty weight. Something to remember, most homes in the United States have floors that can support a koi pond with a water depth of around 18 inches.

Don’t choose a space by bookshelves, furniture, or other obstacles. It makes it harder to change the water and look for possible leaks. It’s also a good idea to keep the pond away from electrical outlets.

Placing the pond in areas kids and pets play in is never a good idea. Find a space that’s out of the way. I also spent a few hours training my kids and dog to stay out of the water. An indoor pool screen will also help, especially if there are cats inside.

A Photo of a Minimalist Pond Indoors
Create Sufficient Space to Install Your Indoor Koi Pond

Designing An Indoor Koi Pond 

An indoor koi pond design can be whimsical, eclectic, or sophisticated. Indoor koi don’t care what their ponds look like as long as pH levels are acceptable. Have fun and use your imagination. The ideal is to create a space to enjoy and relax in.

Design the Size of the Indoor Pond 

We know water is heavy, a little over eight pounds per gallon. The weight the flooring can support and the dimensions of the space determine the size of the indoor pond.

I’m not great at visualizing how the pond will look in my space, so I used cardboard boxes to simulate its general size. It’s a lot easier to add or remove a box than redesigning an indoor koi pond.

Also, think about the pond’s shape. It also affects its weight. You should spread the water evenly across the pond, so don’t incorporate interesting slopes and angles into the design.

Three Different Kinds of Koi Fish - Two With a White Base and Black Markings and One with Orange and Black Markings
Come up with the Design of the Indoor Koi Pond You Want In Advance

Select the Koi Pond Materials 

Designing a koi pond inside the house starts with in-ground materials. Concrete or mortar are the most common building materials. They are durable, water-proof, and are made to last for years. Sometimes longer than the structure’s foundation.

The frame is the next step. It’s the above-ground part and is usually constructed from wood. Any paint or varnish used to change the natural color of the wood needs to be safe for aquatic life. When in doubt, ask a koi specialist or the builder.

Now it’s time for the fun part, decorating the inside of the pond. My koi don’t care what’s in their pond. Chances are yours are just as blasé about the decorations.

Don’t forget to include aquatic plants to aid with filtration. Some plants will also help keep pH levels balanced without the need for added chemicals. Trust me, anything you can do to reduce pond maintenance is beneficial.

Rock, tile, wood, and stone decorations all look great in an indoor koi pond. The fish may also enjoy swimming around and under the decorations. Giving the pond a personal touch makes it more enjoyable. Think of it as creating a private mediation spot.

A pond liner is a necessity. Don’t skip it and depend on the pond’s construction. Use polystyrene to line the frame. Its dark color enhances the koi’s bright colors, and the lining prevents tears, punctures, and minor leaks. Prefab indoor koi ponds usually come with a liner, but it’s a good idea to double-check. Fishy-smelling water spreading across the floor is never fun to clean up.

A Koi Pond with a Plant in the Middle
Give Your Pond a Personal Touch

Other Building Considerations 

During the indoor koi pond design stage, it’s a good idea to think about bolting the above-ground frame together. It doesn’t allow the pond to move to various rooms, but it does make it easier to disassemble. You may need to remove the frame for repair work on the sides or bottom.

The pond’s design should include space for a six-inch gap between the edge and the surface of the water. Koi like to jump out over the edges. My cat watches and anxiously waits for the next snack to leap out. Leaving a six-inch gap keeps my koi in the pond and my cat surviving on cat food.

Consider Finding Indoor Koi Ponds for Sale 

Designing an indoor koi pond is fun, but it’s not for everyone. It takes time, a lot of research, and finding the right people and materials for the job. It is easier to purchase a pre-fab one, and it’s not hard to find some great indoor koi ponds for sale.

A Group of Koi with Their New Breed and a Turtle
You May Customize Your Own Koi Pond


Instaponds are exactly what the name implies. Most are custom designs differing by shape and dimension. Glass is the most common material used. It’s similar in appearance to a koi tank.

The tank comes fully assembled. Place it on the floor and plug the lights and filtration in. It’s one of the easiest and most convenient ways to get an indoor koi pond.

Fountain-Style Koi Pond 

Small spaces are ideal locations for a water feature such as an indoor fountain pond. The size of the basin varies, making it easy to find one to fit almost any space. Smaller fountain ponds will hold two or three small koi, similar in size to aquarium goldfish.

Adding some aquatic plants like spiral bamboo gives the pond a meditative feel. A small bamboo water fountain will complete the look. Koi ponds don’t have to be large for pond plants to be enjoyable.

A Photo of a Brightly Colored Yamabuki Ogon Koi
Creating Your Own Koi Pond can allow you to enjoy your fish year round

Recycled Koi Pond 

Everyone is doing their part to reduce their carbon footprint, including koi ponds. DIY projects often include building koi ponds from recycled materials. Not only is it environmentally friendly, but it’s also easy on bank accounts.

A porcelain bathtub makes a beautiful koi pond. Fill it with floating plants, water, and a couple of koi fish. You can recycle metal bathtubs after coating them with rust-proof paint. Rust can kill koi if flakes fall into the water. Also, smooth over any rough edges around the sides of the tub.

Old wooden barrels make ideal koi ponds in smaller spaces like bedrooms or home offices. Inserting a pond liner will prevent leaks, and adding plants gives the rustic barrel an attractive look.

Another idea is recycling a used plastic swimming pool. I’m thinking about using my kids’ old one. A pond liner is necessary. Just make sure the small pool is deep enough to hold around 14 to 18 inches of water.

Fishbowl Koi Pond 

Fishbowls are available in all sizes and styles. All are round, but some are elongated for a unique appearance. Most also come with stands. It’s a convenient way to display the koi.

Bowl koi ponds usually only hold one or two fish. Remember, koi need plenty of space to prevent disease. Most bowls are large enough for a few plants and decorations to help with filtration and add visual appeal. 


There are many ways that you can keep your koi indoors - some living arrangements are better (and healthier) for your koi than others. It would probably be worth your time to contact koi pond building experts in your community who can give you great advice and help install your indoor koi environment. Use our Koi Pond Service Providers directory to find a professional near you.

Frank Salvatore

In 2015 our family moved into a house south of Denver, Colorado with a  koi pond.  Since that time I've learned to really enjoy the koi fish and the pond. This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?

About Me

Hey there - I'm Frank Salvatore. In 2015 our family moved into a house south of Denver, Colorado that had a Koi pond. The problem was I knew absolutely NOTHING about koi ponds.

This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?
Learn More About Me

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