Koi Ponds

Koi Ponds

Several of the places I’ve lived, including San Francisco, have had Japanese tea gardens, and I have always found a kind of unrushed deliberateness in them.  Everything is precise and orderly, and yet at the same time relaxing.


Within these calm environments, some of my most treasured memories are of the koi.  They move slowly and deliberately through the water– only to suddenly grab a fleck of something tasty from the surface and dart back down with a splash! Their Japanese name, nishikigoi, means “brocaded carp.” This is appropriate, as they are bred from common carp, and are kept for their beautiful, often patterned, colors. Also, the Japanese word koi (which means simply “carp”) sounds the same as the Japanese word for affection or love. For this reason, koi have become symbols of love and friendship in Japan.


Varieties Over two hundred years of breeding, these beautiful fish have gained astonishing variety in their coloration. Colors can include white, black, red, orange, yellow, blue, and cream, or a combination of several. They can be spotted, splotched (my favorite), lined, patterned, or have a highlight color picking out the edges of their scales. Varieties of koi are mostly distinguished by their color and markings:

  • Kohaku—white with large red markings on top. This variety was the first to be developed in 19th century Japan.
  • Taisho Sanshoku—like Kohaku, but with additional black markings.
  • Showa Sanshoku—black with red and white markings
  • Tancho—this is a special name for any koi with a single red patch on its head.
  • Chagoi (“tea-colored”)—earth-toned, including dark green, brown, copper, or bronze.
  • Asagi—light blue on top, red, yellow, or cream-colored below.
  • Utsurimono—black with white, red, or yellow markings, frequently in zebra stripes.
  • Bekko (“tortoise shell”)—white, red, or yellow with black markings.
  • Goshiki—dark with patterned red markings, sometimes in fishnet pattern.
  • Shusui (“autumn green”)—pale blue-gray above, with red or orange below and on the cheeks.
  • Kinginrin (“gold and silver scales”)—metallic, with a glittering, metal-flake appearance.
  • Ogon—solid-color metallic, including gold or platinum.
  • Kumonryu (“nine tattooed dragons”)—black, patterned scales with curling white markings, named for Japanese ink dragon paintings.
  • Ochiba (“fallen leaves”)—light blue or gray with copper, bronze, or yellow patterned markings.
  • Koromo—White with red markings on top (similar to Kohaku) with blue- or black-edged scales.
  • Hikari-moyomono—colored markings over a base of one or two metallic colors.
  • Kikokuryu (“sparkle black dragon”)—similar to Kumonryu, but with a metallic base color.
  • Kin-Kikokuryu (“gold sparkle black dragon”)—similar to Kikokuryu, but with a Kohaku-style pattern of markings.
  • Hybrid Koi—varieties bred with other types of carp
    • Ghost koi—metallic colored.
    • Butterfly koi—long, flowing fins.
    • Doitsu-Goi—Bred with German scaleless carp, these fish have sometimes have scales missing from their bellies and sides, and one very rare variety has oversized scales.

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What You Need to Know As you can see by the extensive list above, there is a lot to know about Koi.  In this short article we cannot tell you all you need to know to make or even maintain a pond of healthy, happy, beautiful koi. The best we can do here is to provide some tips to get you started in the right direction and provide some links to explore on your own. If you think a koi pond is right for you, consult with an expert to build a pond that will give you years of relaxation.

1) Pond/Fish Size If you have a pond that was originally built for decoration or to house a few goldfish, it might not be right for koi. Remember that koi grow, and need more space and more oxygen as they grow. The full size of a koi varies with the space, food, and water conditions. A typical koi can grow to 18 inches in three or four years, and live 25 to 35 years, but rarely more than 45. Under the right conditions, koi can grow to three feet in length. There was one documented case of a scarlet koi named Hanako that lived for 226 years!


The fish should have room to freely move around. This not only allows them a healthy amount of exercise, but their natural darting and leisurely meandering is far more pleasing to the eye than a crowd.  As far as numbers go, a common rule of thumb is 250 gallons per koi, though with filtration you can get by with less. Every cubic foot contains 7.5 gallons of water.   The water must be at least 18 inches deep, and deeper is always better. Also, having at least six inches between the pond rim and the top of the water discourages predators (which can include birds of prey!) and prevents the fish from jumping out of the pond.

2) Filters A filter is necessary to keep pond water clean and aerated, and must be running at all times. Ideally, you want a spare pump in case of failure. Plan for future growth, and choose a filter with enough capacity to keep the water clean.  Even if the water is clear, clean the filter according to the manufacturer’s instructions. Be careful of using filters designed for pools; they are optimized for running for a short period once a day, and running one all day long can get expensive.  Consider adding a waterfall to your pond; it aerates the water naturally, and makes a beautiful, relaxing sound.

3) Liners Liners are available made out of materials such as PVC, but it is almost impossible to eliminate wrinkles and folds in the liner, and these will catch dirt and other debris your filter cannot easily remove. For the health of your fish, the best pond surface is smooth concrete.

4) Care Be mindful that koi are living creatures, and you will need to take measures to keep them healthy.  Koi are not picky eaters but it’s best to get them food specifically formulated for them. Most owners feed their fish twice a day in summer and once in winter, because they are less active in colder weather. Feed them only as much as they can eat in a few minutes, and resist the temptation to feed them more, as it isn’t healthy for them.   In Sonoma County, it may be necessary to net your Koi pond to keep raccoon and other predators out.

Koi are hardy fish, and can live under a wide range of temperatures, so it is usually not necessary to control the temperature of a pond, but be careful not to vary the temperature too quickly, especially when adding water. For the same reason, when introducing fish to your pond, leave them in the plastic bag they were transported in for at least half an hour. This allows them to get used to the temperature.

(Editor’s Note:  I have, however seen koi suffer from the adverse effects of over-heating (which may have effected their filter).  So please, avoid putting koi inside a greenhouse unless you monitor the water temperature and filter often.) In addition to living a long time, koi are smart fish and can even learn their names!  Think of them as pets.  If a pond is beyond your means, koi can live in an aquarium. All the guidelines above apply. As with a pond, filtering is essential. For additional information consult your local home and garden store might have all the supplies and expertise you need, but there are also many stores that feature supplies and services related to garden ponds, or even specialize in koi ponds.  Several can be found right here in Sonoma County.


(Editor’s Note: koi are beautiful, lyrical creatures that seem to float through the water effortlessly gliding as though they were soaring through a liquid sky.  I’ve spend many happy hours photographing the koi at Empire Nursery when they were located on Guerneville road and had the biggest koi around.  Now your best bet for watching these moving works of art glide is at the The Pond and Garden Nursery off Stony Point Road and Highway 116.)

In addition to these local experts many active forums exist online where koi enthusiasts exchange stories, tips, and advice. Here are a few to get you started:

by Jim Marcolina