Setting up a goldfish or Koi pond can attract many forms of nature to your backyard. The primary thing to remember when setting up your pond is to take your time and plan the pond out so it doesn’t become more of a headache than an enjoyable experience for you. Think about what you want to keep in your pond, such as koi, goldfish, plants, snails, etc. If you want to keep plants then keeping Koi will most often prove to make this more difficult as Koi like to dig in dirt and often eat plants. Goldfish, however, seldom bother plants.
Plants in your pond
If you want plants and fish in your pond it becomes a double edge sword. Plants require lots of light and goldfish and Koi require shade to help keep the pond cooler since they both are cold water fish. Be sure to try and reach a 60% plant coverage of your pond to help block the hot sun from the water. This will help keep the pond cool and the fish much happier. You can use a few Lilies and Lotus which grow very fast, are very pretty and cover a large portion of your pond quickly. Also, incorporate some floating plants such as Water Lettuce, Hyacinth, and Parrots Feather, which offer a great place for fish to spawn on and will also add shade. These plants grow very fast and are wonderful waste removers. Some sewage facilities actually use water hyacinth to help clean out their waste pools! Also remember these plants are not native and are extremely evasive and should not ever be allowed to enter local natural bodies of water. As they grow to such numbers in your pond that you need to remove some simply throw them into your compost pile or garden. They absorb so many nutrients from your pond they are great fertilizer.
You will also want some bog plants such as Water Iris, Bluebell, Pickerel Rush, Lizard Tail, Dwarf Cattails, Arrowhead, Variegated Canna, Horsetail rush, Spider Lilly, and Bog Lilies. These plants will add beauty to your pond as well as a place for dragonflies to land and feel much more comfortable. Dragonflies are a wonderful addition to the pond as they are very aggressive predators of mosquitoes.
Plants are wonderful additions to your pond not only because they help the appearance, but they are like adding an additional filter in your pond. I highly suggest plants in any pond.
Stocking your pond
Be sure to not over crowd your pond. As general rule of thumb if you want Koi you need a 1000 gallon pond to house the first one, then you can add 1 more Koi per 100 gallons of water. These fish get HUGE and if properly kept can live for over two hundred years. They require much better water quality than their goldfish cousins.
Most goldfish can live around thirty or so years. If you decide to go the cheap and simple route and get feeder goldfish to stock your pond do NOT listen to anyone that says most of them will die off. This is often NOT the case. Get how many you want and if you see die off get some to replace them. Feeder goldfish are often not very healthy when you buy them because they have been born and raised in poor water quality and in very over crowded systems. However after removing these goldfish from that condition and getting them into a nice large system with good water quality and feeding a good food for a short period of time their immune system will kick in and they will be almost bullet proof. If for some reason you do have some die off simply go get a few more to replace them. Also keep in mind your goldfish will spawn in your pond so you will often have way more fish than you started with in a short period of time.
For goldfish I wouldn’t recommend more than 1 for every 50 gallons of water. You can do more, however you will need to have a good filter in place to make sure the water quality doesn’t go down hill. In an over crowded system when water quality drops it drops fast and usually deaths will occur from this. In a lightly stocked pond there is less waste and fewer problems with water quality.
How big of a pond should I build?
Good question. Your pond size has a lot to do with what you want to keep and how many fish. If you want Koi these guys can get around 3′ long and 8-10″ wide when they are fully developed. They will require a lot of space. Any way you go be sure to make it big enough so that you will be able to landscape it so that it’s a beautiful part of your yard. It is amazing at how few plants I can get in my 12′ X 12′ 2500 gallon pond.
When you are visualizing building your pond keep in mind that you will visualize it around 30% bigger than it really will be. It’s better to make a pond a bit bigger to start with rather than tearing the system down and rebuilding it next year or just dealing with a pond size you are not happy with. Bigger ponds are actually easier to maintain because the water parameters will be more consistent and fluctuations will be slower than in a small system. Also be sure you check how deep you should dig your pond for over wintering of the fish. In my area ( zone 6-7 ) my pond had to be 3′ deep to be below the freezing line. Deeper ponds are better for the fish anyway so they can hide from predators and stay lower in the water when it’s really hot so they stay cooler.
Be sure when you build your pond it can’t drain into natural bodies of water. North America doesn’t have a single native carp species! They also cause a lot of damage in our natural bodies of water. If you decide to tear down your system or just to get rid of some goldfish or Koi please find someone to give them to and don’t release them in natural bodies of water. This is a horrible thing to do and a crime.
How do I add my fish?
When you have a new system and you start to add fish, don’t add a full stocking level at once because at that point there isn’t any nitrafying bacteria established yet. Please see my article on the Aquatic Nitrogen Cycle as it also applies to ponds.
It is often difficult to cycle a pond with the ammonia method mentioned in the link above. Since a pond is generally such a big system, simply adding a few fish at a time won’t be a problem. At first add 3 fish and wait for about 2 weeks. Then add 3 more and wait for another 2 weeks. Do that one more time for another 2 weeks and your nitrogen cycle should be established enough that you can go ahead and add the rest of the fish. If you are going to do a very small pond, say 300 gallons or less, then go ahead and use the Nitrogen Cycle to establish it before adding any fish.
A pond can be very rewarding and enjoyable. I know my wife and I enjoy ours daily. We not only enjoy our fish and plants but all of the nature that it brings to our back yard. It will attract many insects and animals. If it’s big enough it can even attract some birds that like to be around water. I wish you good luck and much enjoyment out of your new backyard pond.