So You've Always Wanted a Koi Pond Read our article in Aquarium Hobbyist Magazine

With the growing popularity of koi fish over the last 10-15 years, many aquarists have “pondered” the thought of keeping koi themselves. After all, it’s easy to see why they are known as “Living Jewels” amongst koi enthusiasts. Their vibrant colors and constant movement provide a tranquil and calming affect to all who view them.  Many aquarium shops now keep at least some variety of koi in their inventory because they are such a hardy and docile fish that will enhance almost any fresh water aquarium or outside garden pond.  Because koi can grow over 3 feet long, aquarists usually transplant their koi to larger outdoor garden ponds when they outgrow their aquarium.  Koi are best viewed from above, so many add them to the pond right from the start.

A Brief History of Koi

Koi fish are carp that were largely bred for food throughout the Asian continent. The beginning of the colors we see today originated in eastern China over a thousand years ago. This date is debated among experts today as there is evidence of their existence 2,500 years ago. Whether by design or by happenchance, a mutant colored carp was matched with another carp and unique colors emerged.  Although many mistakenly believe koi and goldfish are the same, they actually come from different families. Goldfish are mutations of Crucian Carp (Carassius Carassius) while koi come from common carp (Cyprinus Carpio). About 1830, Japanese enthusiasts started experimenting with koi by cross breeding them to enhance their various colors and shapes. This resulted in the brilliantly colored Nishikigoi (brocaded carp) we enjoy today.  Ojiya City in the Niiagata region of northern Japan leads the way in producing the world’s finest koi. If kept in the right environment, koi can live up to 35 years. The oldest known koi on record lived 226 years and was from Japan. Her name was Hanako.  She died in 1977, was over 3 feet long and weighed 20 pounds. AMAZING!

Varieties of Koi

Experts differ as to how many color patterns of koi exist, but most agree that they stem from 12 or 14 basic varieties. Most common are the Kohaku, Sanke and Showa varieties, but there are hundreds of sub varieties. The elegant butterfly has become more popular in koi shows recently.  A unique variety which reflect a metallic shine are called "Gin Rin".  Those which have no scales and are smooth to the touch are of German descent called "Doitsu".  The Ogon variety refers to a solid color which can be platinum white or deep orange.

Where Can I Find Koi?

Koi, in general, are placed into one of three grades. Show, Select, and Common quality.

Not surprisingly, most people don’t wish to pay the high price of show quality koi from Japan. Their costs can run into the thousands.

Select quality koi are still from Japan but more within everybody’s reach.  Both the show and select quality are found in designated koi stores.

The most affordable are the common variety.  They are sold in aquarium stores and the big-ticket pet stores such as Pet Depot or Petco. Just like many other types of domesticated animals, they make wonderful pets. Common koi often come from Egypt, China, Sri Lanka, Singapore, Malaysia, Thailand, and the Philippines.

Selecting Quality Koi Fish

Selecting koi is no different than choosing any other wet pet. Unless extensive research is done on all the different varieties and their subtle differences, it often comes down to choosing the one that appeals to you the most.  The important thing to consider when buying koi is to avoid buying sick fish. Choose reliable dealers.  Ask if their fish were quarantined and for how long they’ve been in inventory.  If a fish hasn’t sold for a while, perhaps others have passed on it for a reason.  If it’s possible, after purchasing, try to quarantine any new fish for a few days before adding them to your pond.

Feeding Your Koi

The art of feeding koi can be both an enjoyable and satisfying experience. Unlike humans, koi have no stomachs.  So, depending on the time of year and the type of food they ingest, it can either sit in their gut or be eliminated through their natural digestive processes. If allowed to sit in their gut, tumors can develop. If the food is digested naturally, the fish can absorb all the healthy benefits of the food.  Do not overfeed your koi. A basic rule of thumb is to feed your koi only what they can eat in 3-5 minutes. How often your koi are fed in a week is determined by the water temperature. When water temperature drops below 50 degrees, stop feeding them altogether.  Generally, feed them 2-3 times a week in temperatures between 50-60 degrees and 2-3 times a day in temperatures above 70 degrees.

Different Types of Koi Ponds

Koi fish are highly adaptable. Given both adequate water circulation and filtration, they can survive in most any environment. But because koi grow so large, providing sufficient oxygen is most critical. Through the years, I have seen koi survive in anywhere from whiskey barrels to million-gallon lakes. However, most backyard ponds average about 1-3 thousand gallons. They are usually constructed out of either concrete or urethane liners. As one might expect, concrete ponds cost more to build, but will last for years. Within the last decade, liner ponds have become very popular to many homeowners. Complete pond kits along with video tutorials on how to build them are now available for Do-It-Yourselfers.  Or, if one desires, many installers can be found online that will take your pond to the next level.

Koi Pond Pumps and Filters

Pump circulation and filtration play the key role in achieving pond balance.  Properly matched pumps and filters provide the oxygen and beneficial bacteria needed for good fish health and water clarity. The two types of pumps that dominate the industry are submersible and above ground.

Submersible pumps sit at the bottom of a skimmer box and pull water through a net to trap large debris. Then it flows up to the bio-filter box at the top of the waterfall, through several filter mats, then down the waterfall returning to the pond. These type of systems address both the need for filtration and the oxygen demand required for the fish.  The great advantage of this type of system is pump noise reduction.

 Above ground pumps and filters accomplish the same goal as submersible pumps. These pumps have pool-like skimmer baskets which collect debris. The pumps are usually located outside the pond area. Previously, inefficient costly single speed pool pumps were used with old style sand filters. But recently, because of their efficiency, sales of variable speed pumps have become popular. They allow one to “dial in” precisely the water flow needed passing through the filter. This saves on energy usage considerably.  There are several types of above ground filters available today. The most common type is either pressurized bead filters with backwash valves or up-flow biological filter mats.

Ultra Violet Lamp Units

Ultra Violet lamps are also an important element for water quality. They are highly effective for controlling green planktonic algae. Ultra Violet lamps work by killing unwanted bacteria as the water passes over an ultra violet lamp housed in an elongated tube. Because the bulb intensity diminishes throughout the year, they should be replaced annually.

Water Testing

As with aquariums, the water should be tested often. Since koi produce a significant amount of waste, ammonia and nitrite levels should be kept as close to zero as possible. They prefer Ph levels between 7.8–8.4. Koi are a hardy fish and can survive water temperatures from freezing to 85 degrees, as long as the change is gradual and certain precautions are taken.

Aquatic Plants

By adding shade and removing nutrients from the water, aquatic plants play an integral part of the balance in a pond. They complete the nitrogen cycle by converting ammonia to nitrites, then to harmless nitrates that are taken up by the plants. They also add protection from predators and provide food for koi.  

Aquatic plants are categorized into 4 groups including:       

• Water Lilies:  Hardy Lilies, Tropical Lilies and Water Lotus
• Marginals:  Water Canna, Taro, and Water Iris
• Floating Plants:  Hyacinths, Water Lettuce, and Water Poppies
• Submerged Plants:  Anacharis, Parrots Feather, and Vallisneria

I prefer to plant most plants in pots to limit overgrowth. But if they are trimmed and kept under control, marginal plants do very well along shorelines.

TO SUMMERIZE, the insights offered here are a general overview of the pleasures of owning a koi pond. But, in fact, this article only touches on a few of the many facets of koi keeping.  Has your interest been piqued?  Don’t be afraid to dive right in!  Quite possibly, it might ignite your passion for the JOY OF KOI.                                                                                                                  

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