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Building a Backyard Koi Pond: How We Built Our Little Water Garden Around Rocks and Under Trees

Anthony enjoys spending time in the workshop, kitchen, garden, and out fishing. Many of his DIY projects are featured in his yard.

Our Pond is a Very, Very, Very Fine Pond

Our small backyard pond is home to goldfish, koi and frogs

Our small backyard pond is home to goldfish, koi and frogs

Building a Garden Pond Is a Fun and Rewarding DIY Project

Our small garden pond is tucked between an outcropping of natural granite boulders and under several large oak trees. While most guides for creating water gardens and backyard ponds recommend building garden ponds on a flat, level area in full sun and away from trees and rocks (and this is very good advice), our yard does not offer such optimal conditions. But this did not stop us from building a successful, unique and beautiful garden pond that is filled with healthy plants and fish, and has rewarded us with years of enjoyment.

Left behind from the retreating glacier that covered the Northeast during the last Ice Age, the granite ledge and large rock outcroppings in our backyard provided a dramatic backdrop for building a little garden pond. A gap between two boulders left a natural trough that was perfect for building a little stream to trickle down towards the pond, cascading over the edge of a waterfall and then spilling into a small pond that we dug out between the rocks and contained with a cinder block retaining wall.

Building this small garden pond in an area surrounded by ledge and boulders, under trees and on a slight slope was a challenging project, but it was a lot of fun too.

Plants help to keep the water clean, give fish shade and places to hide, and they look good too.

Plants help to keep the water clean, give fish shade and places to hide, and they look good too.

Preparing the Site

We used a garden hose to layout the perimeter of the pond. When building your garden pond, outline as large an area as possible; though the pond may seem huge initially, most pond owners wish that they had made their pond a little larger and a bit deeper. Our small garden pond is a teardrop shape, approximately 11 feet long and six feet across at the longest and widest points, and just over three feet deep.

Since we were digging the pond into a slight slope and around huge chucks of immovable granite rock, we marked the highest point that would indicate the surface of the pond, and then used a string with a line level to determine which sections of the pond's edge were below this point. This gave us an idea of the angle of the slope, and the height of retaining wall need to contain the low end of the garden pond.

The low point of our garden pond was nearly 24 inches below the highest point near the water fall. To contain the water on the low end, we built a low retaining wall with dry stacked concrete block, and then covered the block wall under a berm of dirt.

Digging in

Digging the hole for our small garden pond was a manual effort, one shovel full of dirt at a time. Though a renting or hiring backhoe would have made the job easier, locating our pond between the large boulders made it difficult to position a backhoe around the rocks to help with the digging. The end result was a lot of shoveling by hand.

We dug down as deep as we could, until we hit a "floor" of ledge rock. We used the dirt removed from the hole to backfill the outside of the retaining wall. The resulting pond is just over 3 feet deep, which is deep enough to prevent the from freezing solid during the winter. Deeper water also helps the pond to stay cooler during the summer months, and keeps the fish out of the reach of predators such as herons and raccoons.

The waterfall in our small pond pours out between natural outcroppings of ledge

The waterfall in our small pond pours out between natural outcroppings of ledge

Laying the Pond Liner

The bottom and sides of the pond are layered with newspapers and old carpet padding to protect the pond liner from tree roots and sharp rock. We purchased a thick rubber roofing liner from a commercial roofing company that we found online, and used it cover the bottom and sides of the pond, adjusting, fitting and smoothing the liner to fit into all of the nooks and crannies. The liner extends up and over the edges all around the pond and well above the high water mark.

The waterfall and stream were lined with more of the rubber liner, cut with a razor knife and fit with sections of rubber liner. We used a specially formulated exterior grade rubber adhesive (often used for rubber roofing) to glue all of the liner seams together, creating a watertight seal. We used the rubber adhesive to glue the rubber liner in place along the rock outcroppings. The rubber adhesive bonded well with the rough texture of the rock, and it has held up well for many years without any leaks.

Add Water

We added layers of chunky field stones to create a rock wall with shelves for plants, and caves and crevices for the fish to hide. The spillway for the waterfall was formed by carefully selecting and positioning smaller rocks. More rocks and pebbles filled in the gaps between the bigger rocks, creating natural cavities and helping to further hide the retaining wall.

As the pond filled slowly, we paid close attention to the liner. Keeping the liner taunt and pressing the liner down against the bottom and up along the sides of the pond as it slowly began to fill with water kept the liner in contact with the dirt floor and reduced wrinkling. Tucking the liner under the rocks that form the capstones along the top edges of the pond holds the liner in place and finishes the edges with a natural look.

The water was murky when we first filled the pond but after a couple of days running the pump and filter, the sediment settled and the water cleared. We waited a couple of weeks before adding fish, giving the pond a little time to naturalize a bit. A waiting period is especially important when using city water, to allow chlorine and other additives to evaporate, and for the water temperature to moderate to your local climate.

After many years, this unconventional garden pond is home to a small but healthy population of koi, goldfish, frogs, and insects. The aquatic plants thrive, though the mostly shaded environment limits the blooms of the hardy water lilies which require full sun. Even with these limitations, the pond and stream offer a year-round water source for the local wildlife. So don't let less-than-ideal yard conditions stop you from building a small garden pond. The results are worth the efforts!

Our Small Garden Pond

Koi and frogs enjoying the pond.

Koi and frogs enjoying the pond.

Buying Pond Fish for Your Garden Pond

A healthy fish has a better chance of surviving the transition and travel from a breeder through distribution in the pet trade and ultimately to your garden pond. When shopping for pond fish, it is important to buy from a reputable and qualified dealer. The big pet retailers may offer the lowest prices on koi and goldfish, but selections of their stock are usually limited to the more popular species that sell in higher volumes. Aquarist specialty shops, koi breeders and garden centers are more likely to cater to intermediate and advanced hobbyists, and these specialists often carry more unusual and exotic types of koi and goldfish as well as the standard breeds.

Examine the condition of the tanks carefully before making a purchase. The tanks should be clean and well lit. Some retailers use a centralized filtration system, while others use individual filters in each tank. Both have advantages and disadvantages, and either can be effective filtration methods when maintained properly. Look for clear, moving water without accumulations of debris. Cloudy water or dead fish left in the tank are strong indicators of problems and should be avoided.

When selecting a fish to buy, look for active individuals with intact fins and bright coloration. Ripped fins can invite pests and diseases, while dull colors or lethargic movements are indicators of poor health. Even the common Comet goldfish have distinctive coloration, fin structure, and movements which can give an indication if a fish is stressed or unhealthy.

After identifying your fish of choice, always ask the salesperson to scoop out the specific fish you have selected. Even in a crowded tank with active occupants, it is relatively easy for an experienced salesperson to single out and net your selections. If the store is busy, it is often to your advantage to let the salespeople help the other customers first so that they will not be as rushed to catch and bag your fish. Ask the salesperson to use large plastic bags and only place one or two fish per bag. The more air and water in the bag per fish, the longer the fish can stay in the bag and the less the temperature of the water will change during the journey home.

Adding New Fish to the Pond

It can take a few days for a new fish to adjust and join the rest of the school.

It can take a few days for a new fish to adjust and join the rest of the school.

Give the New Inhabitants a Good Start in Their New Home

Follow These Simple Steps:

Now that you've purchased new fish, it's time to add them to your pond!

  1. Place the bagged fish into the pond as soon as possible, and then let them float around in their bag for at least 20 to 30 minutes. This time will allow the temperature of the water inside the bag to equalize with the temperature of the water in the pond.
  2. If your pond has a shallow shelf, stand or wedge the bags upright and open the top for fresh air water. Adding a little pond water into the bag will help the fish to acclimate further to the pond water.
  3. After the temperatures equalize, gently tip the bag into the pond and allow the fish to swim out. It is not uncommon for the newly introduced fish to seem disoriented, and swim down towards the deeper and darker sections of the pond. It can take a day or two for the new occupants to adjust to their new surroundings and join the rest of the school.

Visit Another Awesome Koi Pond

Beware! Bull frog eat fish!

Beware! Bull frog eat fish!

Bullfrogs are Carnivorous!

Bullfrogs were welcome at our pond—until we saw one attack and eat a koi fish! If you keep koi and goldfish in your pond, beware of hungry bullfrogs.

Purchased from a local gardening center, we added several bullfrog tadpoles to our pond over the course of several years. Bullfrog tadpoles are large by frog standards, and each plump tadpole was about 4" long when released into the pond. Unlike many frog and toad species that morph from tadpole to adulthood in a single year, bullfrogs spend the first year of their lives as tadpoles. They happily rooted around along the bottom of the pond and between the rocks, searching for food and picking at the algae.

The tadpoles begin the familiar transformation towards becoming a frog during their second year. First, small rear legs appear just under the tail. Then the front legs emerge and the tail begins to shrink as it is absorbed into the growing body of the bullfrog. Before long, we had several bullfrogs living in our pond, along with the frequent visits from small spotted frogs, wood frogs, and spring peepers.

The bullfrogs grew quickly throughout the summer, and most survived the winter under the frozen surface of the pond. After a couple of years, one frog, in particular, grew into a very large, adult bullfrog. We dubbed him Mega Frog, and he usually sat on top of the lily pads in the middle of the pond.

We have a few small koi in the pond, along with with several Sarassas, Shubunkin and comet goldfish plus a handful of small golden feeder fish. The goldfish breed prolifically, and each spring brings a new swarm of little black fry. Occasionally, a fish goes missing when a raccoon or heron grabs a meal. It's sad, but not alarming as some losses are expected to the local predators.

One evening, Mega Frog was perched on his lily pad when we came down to the pond. We always feed the fish from the same overhanging rock, and the fish congregate around the edge of the rock when we approach, looking for their handout of pellets.

This time, as one of our butterfly koi slowly swam past the lily pads, Mega Frog struck. The water in front of the lily pads exploded in a splash and a fraction of a second later, the bullfrog was sitting on a rock with just the forked tail of the koi hanging from his mouth.

Now, Mega Frog and the other bullfrogs live in a large natural pond on a friend's property.

The local wood frogs and peepers are still welcome visitors to our small garden pond, and they do not seem to bother the fish. Since removing the bullfrogs, we've seen more native peepers and wood frogs in our pond - they must not like bullfrogs either!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2011 Anthony Altorenna

Tell Us About Your Garden Pond

Karlene on June 04, 2020:

I need to make my pond larger but my koi fishes are huge and im afraid to take them out how then can i make this pond larger

the soon-to-make pond builder. on July 24, 2019:

Dear Anthony. I'm only 11 and would really like to build a frog pond. I've already built the hole. what I really want to build is a natural frog pond. u know. one that doesn't have a plastic sheet at the bottom. will rain water make my pond muddy? and what temperature does the water have to be?

from: the almost-pond-builder.

Anthony Altorenna (author) from Connecticut on December 31, 2014:

Hi Alex, thanks for stopping by. Positioning your pond under a tree probably won't help protect the fish from predators. My pond is located under trees, and the occasional heron still finds it. You will need to remove the falling leaves from the pond to prevent the leaves from decomposing in the water. Digging the pond at least three deep and lining the sides with rocks to create nooks and crannies for the fish to hide in with help to keep them safe. Good luck with your pond!

Alex Sinkamba on December 26, 2014:

I have a pond positioned under a tree to protect my fish from predators : blue herons. Will this affect fish health ?

ismeedee on June 30, 2014:

Your pond looks lovely! We recently created a wild pond in our community garden. We aren't having any fish because we only want was is indigenous to the area. We found an ancient wild pond and took weeds and microorganisms from it to get our pond going.

GrammieOlivia on June 18, 2014:

Mine is about 2,500 gallons and home to many goldfish. We gave up on the Koi because we found ou t that they were like Sushi for the Racoons. Now we enjoy the goldfish instead and if they happen to become some critters dinner, they are not too expensive to replace.

LadyDuck on May 19, 2013:

I love your pond, it's much better than mine. I have a lot of work to do, I like water is so relaxing.

anonymous on October 24, 2012:

Ponds are so relaxing, and yours is beautiful. Thanks for explaining about bullfrogs being carnivorous. I didn't know that.

GardenIdeasHub LM on October 24, 2012:

I was very interested in building a small garden pond and i agree with you that it's fun and rewarding project.

Mary Stephenson from California on October 06, 2012:

I heard that bull frogs are very noisy. I don't blame you getting rid of them out of your pond. They were feasting on some pretty expensive fish.

AshleyCarew1 on October 06, 2012:

Looks and sounds great! Thanks for laying it out in so much detail. The little lady sitting by the pool looks like she is going to enjoy watching it team with life as she grows up!

Missmerfaery444 on October 05, 2012:

Wonderful! We have a toddler at the moment so only have a small water feature, but would love to have a proper wildlife pond one day!

Stuwaha on October 05, 2012:

This was a genuine pleasure to read! I know of someone who moved into a property that had a small pond however no one knew it was there because the garden was so overgrown and unloved. When they cleaned up and discovered it there were still living Koi inside!!!

getmoreinfo on October 05, 2012:

Your garden pond is very nice, I like the location and the tall trees around it too.

anonymous on October 05, 2012:

Would love to have a Pond of my own maybe some day in the future.

techmom on October 05, 2012:

I didn't know that bullfrogs eat fish! That really surprised me!

Deadicated LM on August 22, 2012:

Thanks for all the great info; your pond is awesome!

Gayle Dowell from Kansas on August 19, 2012:

I'm enjoying all of your garden lenses. I've got a small pond in a small garden. I'd love to build a bigger one.

Lorelei Cohen from Canada on July 30, 2012:

I'm just stopping by to relax by your backyard garden pond for a few minutes. (I had no idea that bull frogs ate fish.)

anonymous on July 27, 2012:

I would like a pond, but it sounds like a lot of work and would not want a dirty pond or dead fish - it sure is pretty.

ArtBoogy on July 27, 2012:

Thanks for all the info and resources. I thought I would add a resource and mention this crystal blue pond dye I used for my pond.By the way, I had no idea bull frogs were carnivores!

anonymous on July 18, 2012:

I hope to have a garden pond someday, I have a lot of projects that have priority over it right now though.

anonymous on July 12, 2012:

I was in your neighborhood and you know how I love your small garden pond!

Sher Ritchie on July 05, 2012:

I LOVE your pond - it's amazing! Thanks for sharing so much detail about how you built it, and stocked it. I love ponds (per se) and your's is a champion!

Tony Payne from Southampton, UK on June 10, 2012:

This just looks wonderful, you must have a large garden to work with. I always wanted a garden pond, but our garden is fairly small unfortunately, with little scope to build one. Your instructions are very clear and detailed, and I love the photos too.

Anthony Altorenna (author) from Connecticut on June 01, 2012:

@JGracey: Hi, and thank you stopping by! Our pond gets lots of wildlife visitors. Most our welcomed, but we also get the occasional trouble-maker including herons and raccoons that prey on the fish. Last winter, an unwelcomed guest feasted on our koi and goldfish, which was very sad -- a few of the koi were at least five years old. Fortunately, this does not happen often, and we added new fish to the pond this year.

JGracey on May 27, 2012:

I really enjoyed this - we have a pond but nothing like this one. We have one of those purchased, pre-formed ponds. It's about "knee deep" and kidney shaped. The first year, we put in water lily plants, but the skunks and raccoons ate them. I tried koi once, and all that did was feed the feral cats in the neighbourhood. Last year in early spring I noticed little moving "things" in the water ... tadpoles. No clue how they got there but we had a small spotted frog in the pond all last summer. Late fall we tried many times to catch him and take him to the marshes, cause we knew he wouldn't survive the winter in the pond - no mud in it for him to burrow and hibernate. Missed him, or he slipped out of the net or our hands every time. Sadly, he was a floater this year when the ice came off the pond.How do you keep animals out of your pond?

Satdin on May 14, 2012:

It is my obsession to spend spare time beside my pond. I love it.

Spikey64 on April 19, 2012:

My garden pond is a great place to relax and unwind after a hard days work. Great lens thanks for sharing it with us.

anonymous on April 12, 2012:

Was just passing by and had to make a stop at your small garden pond...sigh...

MindPowerProofs1 on April 01, 2012:

I love watching and listening to the water. Great advices.

Mary Norton from Ontario, Canada on March 29, 2012:

You make this easy. I love garden ponds.

anonymous on March 25, 2012:

I was just passing through your yard and just had to pause to enjoy your small garden pond once again....I would be sitting there all the time when not at the fire pit!

James Jordan from Burbank, CA on March 18, 2012:

Thanks for the inspiration. We have a pond but it drained because our dog jumped in and punctured the lining. So, I haven't fixed it yet because I haven't decided if I want to just fix it and go on or create a bigger, more amazing one. I think I need to just get it going.

Einar A on March 18, 2012:

That looks like a nice little spot, and you've provided so much information for anyone who might want to build their own pond!

lunagaze on March 14, 2012:

Great guide. I would love to build onto my existing pond and add fish to it

Joy Neasley from Nashville, TN on March 14, 2012:

Here in China we have a Koi pond in the backyard. It is very beautiful, but not something I would not have done myself if it had not been there when we moved in. Now I love it and the peaceful atmosphere it provides. I look forward to feeding the fish and talking to them as they come to get the food from me.

KarenCookieJar on March 13, 2012:

You did a great job, it looks so natural, like it had always been there.

anonymous on March 12, 2012:

Very cool article. I want a pond, but are they a lot of work?

julieannbrady on March 05, 2012:

Gosh, I thought I'd visited before, but can't find my comment. But here I am again! I know that I have got a perfect backyard for a pond, and other things. The sellers made a point of telling me, you got plenty of room for a swimming pool. However, I've got 4 giant water oaks which drop a lot of nuts!!! and leaves throughout the year. Plus lots of birds and squirrels. A garden pond sounds perfect. Do you travel?

Lee Hansen from Vermont on March 03, 2012:

We have two small garden ponds at our Pennsylvania house along with several drainage streams, We had 24 goldfish raised from birth for 8 years, but a heron got 'em last spring. At our Vermont house we have a natural rocky brook that's pretty wild and overgrown. We're tackling the cleanup this summer and will be adding plants but not fish.

Rosaquid on March 02, 2012:

Thanks for the lovely lens. I want to qualify my vote: I am only planning to build a backyard pond IN MY DREAMS! Your lens is a real dream-feeder, though!

AJ from Australia on March 01, 2012:

Garden ponds are such romantic, peaceful spots for all those who seek their solace.

Elyn MacInnis from Shanghai, China on March 01, 2012:

Your lens made me so happy. I felt like I had been to a park. I do have a small pond in the back yard with a small waterfall. The sound of the water is so lovely. It helps mute any sounds from the street, and gives our lovely bird friends a place to come. The thing I worry about is keeping the pond sufficiently clean. We do take all the water out that we can and then refill it each year, but it still seems dirty in spite of the pump and filter.

GreenMind Guides from USA on February 29, 2012:

Nice lens! I would love to have a pond in my back yard.

QuiltFinger from Tennessee on February 28, 2012:

Wow. Your pond looks fantastic! I was really surprised about the bullfrog anecdotes. I had no idea. Thanks for much for sharing! :)

intermarks on February 28, 2012:

Your garden pond is really awesome, I wish I can make one like yours.

anonymous on February 27, 2012:

I love your new little pond, ours is somewhat larger so our landscaper asked us to "season" our new pond first with guppies, then the next year we could add fish. We chose bluegill to catch bugs and catfish to keep the bottom clean - they are so much fun. Then some big birds flew in and ate all the fish, time to start over !!! Thanks for sharing too !!!

Sandy Mertens from Wisconsin on February 27, 2012:

Very nice!

macsquared on February 25, 2012:

My dad in CA has a backyard pond with koi in it. I love koi, I think they're so beautiful! I'd like to have a backyard pond someday, I think.

Anthony Altorenna (author) from Connecticut on February 25, 2012:

@Scotties-Rock: The local wood frogs and peepers are welcome visitors and they do not bother the fish. The bullfrogs were purchased as tadpoles, before we learned that they will eat fish as adults. Since removing the bullfrogs, we've seen more native peepers and wood frogs - they must not like bullfrogs either!

Clairissa from OREFIELD, PA on February 24, 2012:

Beautiful pond. I am beginning to get spring fever and want to go out and work on mine, but its still too cold. I have frogs too they do make it interest. At night the frogs hop on over to my pool to take a midnight swim. Unfortunately the little ones can't get out and drown. Poor little fellows.

madoc on February 23, 2012:

Very useful - I have ot rescue a derelict pond at our new house. This gives me some starting points.

MissingPersonso on February 22, 2012:

I thought maybe a bird was getting my goldfish, but now after reading this I realize it was the frog that grew from a tadpole to a bullfrog in the pond.

A RovingReporter on February 21, 2012:

I love koi and I love koi ponds.

fullofshoes on February 21, 2012:

Beautiful backyard pond.... and great storytelling.

anonymous on February 20, 2012:

Always wanted one of these, enjoyed viewing and thinking about this.

saerae01 on February 20, 2012:

You have me wanting a backyard pond. I always thought they could only be at most 1 foot deep. Now I know they can be way deeper.

anonymous on February 20, 2012:

Congratulations on front page honors for your Our Small Garden Pond, it sure is one of my favorites and I dream every time I stop by!

pawpaw911 on February 20, 2012:

This lens was just as enjoyable the second time I looked at it, as the first.

Jules Corriere from Jonesborough TN on February 20, 2012:

What a lovely garden you have. Beautiful lens! Thank you for sharing this.

caketech on February 20, 2012:

I would love to have a garden pond! Circumstances prevent us from building one right now, though. Maybe one day we will be in a position to build one. Thanks for sharing your experience with us!

flicker lm on February 18, 2012:

Thanks for sharing your story and photos of your lovely pond. Sorry you had to send Mega Frog away, but I'm glad you found him a good home. :)

Fay Favored from USA on February 17, 2012:

My attempts to have a pond were short lived due to our pets. However, I may try again one day in a new location. Thanks for sharing your garden pond with us.

Coreena Jolene on February 15, 2012:

I wish I could have a pond. I didn't know the frogs would eat the fish! We have frogs show up in our yard, my husband says they are toads and they get in the swimming pool. They can't survive the clorine though. Your pond looks lovely, very relaxing and I bet it is fun to feed the fish.

anonymous on February 10, 2012:

I would love to have a pond in my backyard

hamshi5433 on February 03, 2012:

aww im jealous of your garden pond! our garden is pretty much empty right now and because of the mad weather here, we really can't do anything about it at the moment..I would love to have a beautiful pond in my garden soon some day.

Anthony Altorenna (author) from Connecticut on February 03, 2012:

@anonymous: Hi FlowerGardner, and thank you for visiting! Pond liner leaks can be difficult to patch. My pond liner is EPDM roofing material, and I purchased a commercial sealant from a roofing supply house specifically for this product (try searching on Google). It came in a gallon can, and was a thick, sticky black tar-like sealant that I applied with a paint brush. I used the whole can for my project, and tossed it away (sorry!). The trick was applying the sealant over a large area (much larger than the problem area) and applying a roofing material patch over the entire area. So far, I have not had any leaks. Good luck with your repair!

anonymous on February 02, 2012:

Hi Anthony! I love your beautiful pond! I've got one also, but am having trouble with it leaking. Could you PLEASE, PLEASE, PRETTY PLEASE tell me what the name of the sealant stuff is that you used?

anonymous on December 26, 2011:

It was very helpful. My wife wants a pond in our yard like this. It has definitely given me some ideas.

Karen Kay from Jackson, MS on November 17, 2011:

Oh wow! These are so beautiful! I had a small water garden for a while.... it was nice, but not so lovely as these! Thanks for sharing them!

andreaberrios lm on October 25, 2011:

What a great idea!!! A very nice project, thanks for sharing this.

Spikey64 on October 22, 2011:

Brilliant lens. I love to relax next to a garden pond after a long hard day. I just close my eyes and listen to the trickle of the waterfall and all my stresses just melt away.

anonymous on August 10, 2011:

I would like to have a back yard garden pond. I do have a garden pond and fountain in my home amongst my house plants. I love to listen to the sound of water flowing, its relaxing.

Karen from U.S. on June 15, 2011:

My husband has been talking about adding a small garden pond to our backyard. I'll show him this article so he can get a better idea of what's involved. It would be lovely to have one in our yard.

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