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How to Build a Fish Pond

Considerations for Planning Your Pond
An above ground fish pond built under a wood walkway.

Before purchasing supplies for your pond, decide whether you want an in-ground or above ground pond. Also consider your area’s climate. This will help determine how deep your pond should be to support aquatic life in the winter.

 

In-ground ponds:


  • In-ground ponds are relatively simple to install. You’ll need to dig a hole, place an underlayment and liner inside, check for level and adjust, then fill the pond. 
  • To work well during winter, in-ground ponds need to be dug at least one foot below the frost line. 


Above ground ponds: 


  • Above ground ponds don’t require much digging, but you’ll have to build up the sides well to support the pond. Some above ground ponds can be purchased as pre-made pond kits. These may not have the capacity for fish. Instead, they work well as an attractive water garden or simple water feature. 
  • Above ground ponds work well in clay or compacted soil. They're better in climates that don't freeze. 


Recommendations for both types of ponds:


  • Larger ponds tend to be healthier and require less maintenance. The size makes them more chemically and thermally stable. 
  • Pond depths should range from 2 to 4 feet deep, depending on your fish. Fish need space to swim, so deeper is better.
  • Koi ponds should be at least 4 feet deep. The shallowest area or pond shelf needs to have water 2 feet deep.   
  • Goldfish ponds must be at least 2 feet deep if they have no air pump. If you have a pump, you can have a pond depth of 1.5 feet deep.
  • Circular ponds have better water circulation. 
  • In cold climates, provide at least 10 square feet of deep-water space for fish to live in during freezing temperatures. That’s 2 to 3 feet deep or 1 foot below the frost line.
How to Choose a Site for Your Pond
The surface of a fish pond blooms with water lilies and lily pads.

Now that you've decided to make your own fish pond, it's time to decide where it goes. Choose a location that's close enough to your home that you can enjoy the view.

 

Follow these tips to choose the proper place for your DIY fish pond:


  • Check your local requirements for fish ponds. You’ll need to know how far from property lines the pond must be. You may also need a permit to build one or need a fence around it.
  • Avoid digging in areas that have buried cables and power lines. Call 811 to request a utilities worker to mark the location of any buried utility lines on your property. 
  • A pond will have pumps, filters and other pond accessories that require power. Make sure to build the pond near a GFCI electrical outlet. The outlet should be about 10 feet from the pond. Keep electrical wiring in a safe, out-of-sight place. 
  • Don’t place your pond at the bottom of a slope. Water runoff can wash in pesticides and chemicals. This will harm your pond life. 
  • Build the pond near a water source for easier filling and consistent levels. 
  • Place ponds away from trees. Falling leaves and seed pods can clog pumps and filters. Thirsty tree roots will grow through the lining for a good drink.


Considerations when building a pond with fish and live plants:


  • Ponds with live plants should receive four to six hours of full sun. 
  • Ponds with fish or other aquatic life should have some shade during the day. Choose a site that receives approximately equal amounts of sun and shade throughout the day. This provides a good balance of warmth for both the fish and plants in your pond.
Choosing Aquatic Life for Your Pond
An in-ground fish pond filled with koi.

When you’re learning how to build a fish pond, consider your location. The climate you live in is the most important factor when choosing pond plants and fish.

 

  • Strive for a balance of one-third open water and two-thirds plant cover to provide adequate shade for fish. 
  • Goldfish and koi are best suited for home ponds.
  • Don’t overstock your pond. Larger fish, including koi and grown goldfish, need a surprising about of water to thrive. Aim for one square foot of space for each inch of fish. Filtered water can go for one square foot per two inches of full-grown fish. 
  • Koi need much more space than goldfish. A single koi needs 400 gallons of water. A goldfish can live in 100 gallons of water. 
  • If your fish are dying or you see them gulping for air at the surface, the pond may not have enough oxygen. Fix this problem by installing an air pump. 
  • When ice forms on the pond during winter, keep a hole cut in the ice. This allows oxygen to enter the pond for your fish to breathe.  
  • Water lilies, lotuses, irises, water hyacinth and water lettuce are plants that thrive in ponds. 
  • Regularly check the water pH to monitor the toxicity level of ammonia and nitrates. 
  • Try to match the natural habitat for the fish by adding plants they’re attracted to.
  • Native fish and plants are always an excellent choice when building a fish pond.
Building Your Pond
Two people laying a pond liner as they build an in-ground fish pond.

Once you’ve decided on the type of pond, its location and the aquatic life, you’re ready to make your fish pond. 


Figure out your pond’s square footage by multiplying the length in feet by the width. Make sure your fish pond ideas suit the fish type you want. 


Here’s an overview of what you’ll need to create a complete pond:

 

Pond liner: An in-ground pond will need a pond liner to maintain its shape and integrity. Some pond liners are preformed, while others are a flexible PVC sheet that can take on any shape. 

Pond pump: Get a pump to circulate the water in the pond, keeping it cleaner and healthier. The pump should have a GPH (gallons per hour) equal to your pond’s square footage. Pond kits will typically come with an appropriately sized pump. Elevate your pump so it’s not directly on the bottom of the pond.

Pond filter: A filter will help keep the water clean by removing algae and some smaller debris. As with standard pumps, your filter’s GPH should match the square footage of your pond. 

Landscape rocks: Use large landscape rocks to secure and disguise the edge of the pond liner. 

Pond heater: In colder climates, use a pond heater to keep the water warm and comfortable for the fish and plants.


Tip: Turn your pond into a striking water feature using pond light kits or by adding fountain spray heads


Put plants along the perimeter of the water, on the pond shelf. Plants near the middle of the pond work too. As long as they’re in clusters, they’ll look right.

Adding Fish to Your Pond
A woman reaches down to admire a large goldfish in a fish pond.

Gradually introduce your fish to the pond water. Add just a few fish at a time over a few weeks for best results. The water temperature also needs to be what the fish prefer:


  • Let the water settle for 3 days after you’ve added the plants and rocks. If you can wait longer to add the fish, even better. It should look like a natural pond, green and growing, not pristine. The fish need something to eat and a place to hide. 
  • While your pond is growing and settling, buy your fish. It’s best to quarantine them for 3 weeks in a fish tank first. You want to assure they’re healthy and free of disease.
  • Near the end of your fish’s quarantine, add a bit of pond water to the tank. This will help them acclimate when you release them into the pond.


When it’s time to add your fish, you want to assure the water alkalinity and temperature are just right. Also, choose a calm, quiet time to add the fish. Early in the morning, before neighbors start their yardwork is ideal.


  • Check the pH of the pond. Aim for a pH level between 7.2 and 7.8.
  • The water should be clear and at a temperature of 60 degrees Fahrenheit or more.
  • Float the bag with the fish in it in the pond water for half an hour or so. Avoid direct sunlight so the fish don’t overheat. If there’s no shade, shield the bag with a towel.
  • Wait until the bag water and pond water are within 15 degrees of one another. 
  • Gradually introduce pond water into the bag of fish. Take about 15 minutes to do this.
  • Let the bag fill completely with pond water. In time, your fish will swim out into their new home.
  • Quarantine any additional fish for 3 weeks in a tank before adding them with other fish.
  • Repeat this process until all your fish have moved into the pond.
Landscaping Around Your Pond
A small pond brims with floating lily pads and is surrounded by a daylilies and a waterfall.

Hardscaping and landscaping elevate your pond to the next level. Anything hard, like river rocks, stairs or a patio is considered a hardscape. Elements that mimic an ecosystem, including trees, plants and waterfalls, are landscaping. Fish pond ideas inspired by nature often end up both stunning and successful.


  • Add a waterfall: Waterfalls make a beautiful addition to your pond landscaping. However, remember to seal the stones to prevent runoff around the edges. This encourages the water to cycle back through the pond, not get absorbed into the rocks. Leaving a hollow behind the waterfall lets the sound echo.


  • Set some stones: Using large landscape rocks of various shapes and sizes along the outside edge of the pond gives it a finished look. It also provides a place to sit and watch the water, for humans and reptiles alike. A rock wall also helps lessen pond erosion. 


  • Invigorate with plants: Using only stone may look cold. To warm up the landscaping around your pond, add plants. Perennials and grasses add color and movement. They also provide a hiding place for pond creatures who shelter among the leaves.


  • Try driftwood: Use twisted pieces of driftwood to accent waterfalls, special stonework or as a focal point. Driftwood adds a softer texture and enlivens stone structures.


  • Line with paving stones: To decorate a small reflecting pond, use elegant large paving stones. Keep the plants back a few feet to give the pond a place to shine on its own.


  • Make a path with stepping stones: For a big pond, add stepping stones that match the surrounding landscaping. It adds a touch of whimsy and a short path across the water for the adventurous.


When waterwalls, fountains and stone need to take center stage, scale back the plants. Keep them in matching pots to reign them in as needed. Plants in the ground should be away from the waterfall so they don’t get damaged.

How to Maintain Your Pond
A person planting tall green pond plants in a large in-ground pond.

Routine maintenance will keep the fish and plants living in your pond healthy. Have essential pond treatments on hand to keep your pond’s ecosystem balanced. 


Keep in mind that larger ponds with more plants and fewer fish are easier to maintain. Also consider the amount of time you'll need for pond maintenance and upkeep. 


Once or twice a day:

 

  • Feed fish when they're most active. This is during non-winter months only.  


Once per week:


  • Add bacteria to your pond to maintain a healthy bacterial colony. This is especially important if leaves and debris collect in your pond. 
  • Clean water filters. 
  • Drain pond water in cold climates (1/4 or 1/3 of the water) at the start of winter. 
  • Remove decaying leaves and surface debris. 
  • Test the water for excessive amounts of ammonia or nitrites.  
  • At the start of the warm season, turn on the pump and filter. The temperatures need to be consistently above freezing.


Once per month or as needed:

 

  • Fertilize aquatic plants. 


Every 3 to 5 years:

 

  • Service any air pump equipment. 
  • Renew permits if needed. This depends on your county or state.

Knowing how to build a fish pond is a great way to add life and vibrancy to your property. With the proper planning and maintenance, a pond or water garden can be a permanent water fixture. You’ll enjoy it for many years to come. Ready to get started? Find the tools and materials you need with The Home Depot Mobile App