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The Different Ways to Raise Koi.  By Bob & Pam Spindola  Bob and Pam explore the many pond options for keeping these special “jewels.”
Contemplate the graceful movements of the multicolored koi as they turn the pond into a living kaleidoscope. Listen to the sound of bubbling water as a blue dragonfly skims over the surface. These are all ingredients of an outdoor koi pond. Throughout history man has realized the soothing effect these elements have on the human spirit. 
The raising of koi, relatives of the common carp, began in Persia, now known as Iran, many centuries ago. This cultivation spread throughout Asia and came to Japan. It wasn't until the middle of the twentieth century that nishikigoi, which in Japanese means “brocaded silk,” were refined in Japan and accepted worldwide as a hobby. The name is now synonymous for fancy hybrid carp, also known as “living jewels.” 
Koi are related to the clear-water carp fish. They are very strong, eat all day long, and can grow very large. In their natural setting they get all their nutrients from the pond. The lake, because of its large surface area, provides sufficient oxygen gathered from the atmosphere. The filtration is handled by nature in many different ways. When we domesticate koi and want to put them in small pondlike settings, we have to miniaturize nature. We have to provide the same elements that nature would provide, such as filtration, aeration, and food. The basic needs of a koi are as follows: They must have water. The shape of their pond should be elongated, rectangular or kidney shaped with rounded corners. This contour provides a better environment for the fish to exercise. In a small round or square pond, the fish tend to sit in the middle and not move. We liken this to people “swimming” in a pool but sitting, barely moving, in a small square or round spa. 
Koi also need depth of water. They exercise and build girth by swimming up and down the depth of the pond. We recommend a depth of three to six feet. This depth also keeps the temperature of the pond more constant which is better for the koi. Lastly, the depth helps to keep predators away from the fish. Remember, raccoons generally will not bother a pond in which they cannot stand. 
The pond water must be filtered to remove fish waste and debris which falls into the water as well as to keep the water clear for viewing the fish. If the detritus is not removed, toxins are generated which harm the health of the fish. A bottom drain should be installed to remove the heavy waste and gases from the bottom of the pond and carry them to the filter system. In addition, the bottom of the pond should not be flat but gently sloped to the drain. 
In order to add aeration to the water, most ponds have a waterfall. The falling water gathers oxygen and injects it into the pond. Also, we highly recommend venturi jets which introduce more oxygen to the water, as well as add circulation and turbulence. The movement of the water encourages the fish to exercise. In addition, this added water circulation helps keep the pond clean by pushing the debris toward the drain. 
The last component of a koi pond is shade, either natural or man-made. This shade keeps the direct sunlight off the pond in order to inhibit algae bloom. It also protects the pond from radical temperature changes which are unhealthy for the koi. Lastly, it keeps the harsh rays of the sun from fading the brightness of the koi's colors. 
In every culture, there are artifacts or receptacles that were used to hold water, plants, and fish. In our modern day, the garden pond has many interpretations. Ponds can be constructed in concrete, fiberglass, molded plastic, or with various types of liners. We are going to take a look at the many different ways you can create a relaxing waterscape appropriate for koi, keeping in mind their basic requirements. 
Although there are some water gardeners who are concerned only with the plants and do not want hungry and mischievous fish destroying valuable and beautiful water lilies, there are others who want a natural garden habitat that combines both fish and plants. Koi and plants can co-exist with careful planning, a topic which will be discussed in a future article. There are other hobbyists who want the koi to be the stars and do not include any plants in the pond. The following covers many interpretations of the garden koi pond. It is our hope that you will find these examples interesting, aesthetically beautiful, and helpful in designing or remodeling your own pond. 

The Aquarium 
Koi can be raised in an aquarium and make a very beautiful addition to the home environment. Much to our surprise, while walking down a boulevard in Paris, we passed a fish store with some aquariums stocked with guess what?....koi! We were told that many of the living quarters in the city are very small. This is one way of taking care of koi in a city setting with small or no garden area. Although there are benefits to raising koi in an aquarium, the growth of the fish is inhibited by the relatively small environment. 
Koi are very active and need a large area in which to exercise. Even the largest of standard aquariums does not provide such space. Since koi tend to jump in aquariums, the tanks should be covered. Also, an efficient aeration system and good filtration is essential. It is challenging to keep the tank clean and to properly filter the water because of the heavy waste products of the koi. 
Aesthetically, the koi should be viewed from the top. In the aquarium environment the koi are viewed from the side and the patterns are not fully appreciated. All in all, this is an inexpensive and basic way to raise koi, but it is definitely not the ideal way! 

Small Outdoor Receptacles 
These beautiful creatures can be reared in various types of outdoor receptacles. The tub is an example of the small type of outdoor container which can be used anywhere in the garden or patio but is not the best for raising koi. We recently heard from a person who raises koi in a similar tub without aeration or filtration. He claims he has no problems with this set-up. However, his definition of success is arguable as the koi die periodically, and he explains that all he does is merely buy new fish!  
This type of shallow pond is not acceptable nor recommended in raising koi. 
As you recall, the depth of a container should be a minimum of 3 feet. A shallow tub will not provide enough room for exercise. Also, the fish are susceptible to predators as well as to drastic and sudden temperature changes due to climatic conditions. We do not recommend these little tubs, but the koi can survive if you provide aeration and filtration. If no filter is added, many water changes should be made. The use of chlorinated water further complicates the procedure. Also, remember this is a small body of water; you should keep only a few small fish in these small tanks. 
The advantages of these receptacles are the small amount of space required for them and their low cost. Please note that there are larger tubs available which are more suitable for raising koi. 

Larger Receptacles  
Interlocked building logs formed to frame a liner suitable for raising koi because they can be made to a size adequate for raising active koi. Filters and waterfalls can easily be installed. Because the bottom is flat, we recommend a Tetra vac drain which sits on the bottom of the pond and handles the removal of the waste products from the tank and transports them to a filter. These ponds are easily placed in any site from a small patio to a corner in the garden. If need be, they are easily dismantled for moving to a new location. 
Liner material is ideal for koi ponds as it is affordable and very easy to install. In addition to this type of container, however, koi can be raised in doughboy pools, in large troughs, or in fabricated tanks. Filtration, aeration, and even plants are easily added to the larger receptacle. Again, you should keep only a few small fish in these types of ponds. 

Larger Liner Ponds  
Ponds can be constructed with flexible liners in almost any size, from 500 gallons or smaller to over 10,000 gallons. These ponds can have all the necessary components of a well run pond such as waterfalls, filters, drains, skimmers, overflows, and proper depths. 
The pond shown in Photo 4 was built by koi hobbyists in the mid-Atlantic area. It holds over 12,000 gallons and has all the components of a well designed koi pond: a waterfall, bottom drains, venturi jets, and even plants. Notice the double waterfall feeding the pond which has a depth of over five feet. The rocks and design of the pond complement the existing garden. Even in a koi pond, water plants can be added. In this particular pond there are plants encased in PVC rectangle frames lined with mesh to discourage the fish from eating the tender roots. We were recently told that even this precaution did not stop the fish from jumping into the plants. The owners are convinced that the plants need their own stage in a separate pond. The beautiful koi will grow large and healthy in this environment. 
There are advantages to constructing a liner tye pond like this one. Flexible membranes are inexpensive compared to other materials such as fiberglass or concrete. This material is easily installed and easily repaired with tape or patches and special glue. If a larger size pond is desired, more than one liner can be joined or welded to another successfully or custom sizes may be ordered. In geographic regions prone to extremely cold weather or earthquakes, the liner resists cracking and ruptures. 

Formal Above Ground Water Garden Pond  
This is a typical formal, English style concrete water garden which has been constructed above ground. This pond is in full sun to benefit the plants. The owner also raises several koi in the same environment — a real challenge because plants and koi have different needs. Plants like sun, still water, and need very little depth of water. The bottom is usually flat to provide stability for the standing pots. On the other hand, koi thrive in a shaded environment with moving water and in water depths of 3 or more feet. The bottom of a koi pond, of course, should be sloped to a drain to move the waste to a filter. 
Likewise, shade is very important to preserve the fish’s vivid colors as well as to inhibit filament algae growth in the water. The full-sun pond may experience drastic water temperature changes which are unhealthy for the koi. Although the plants in the pond afford shade, as koi hobbyists, we want to see our beautiful fish. We do not want them hiding among the plants! 

Koi and Plants Together 
Even though all these problems exist, koi and plants can live together but only with careful planning of a sound design that benefits both entities. The fiberglass lined pond is an ingenious design of koi and plants together. The owner, a retired architect, has created a koi pond in the center which is surrounded by a water garden. The koi pond has all the elements essential for healthy koi including a shade cover. The water garden which is separated from the main pond by a cement wall is bathed in dappled sun. The water in this area is still and shallow to accommodate the plants. The koi pondwater spills over into the water garden moat. The good aspects of this is that they share the same nutrients; the fish help the plants and the plants help the koi. The drawback is some types of water treatments for koi, such as adding salt, have to be avoided because of the detriment to the plants. We think that this design is a unique way to have the best of both worlds. 

The Tropical Concrete Pond 
This concrete pond is a wonderful example of a tropical water garden. It is a pond with good depth, natural shade, few plants and happy koi. In addition to the natural shade from the tropical foliage, there is a partial overhang to provide even more shade for the koi. However, a sunny area for the plants is maintained. According to the owner, there is no problem having the koi and the plants co-existing in the same environment. 

Small Koi Pond 
This pond, one of our favorites, holds approximately 500-600 gallons with most of the elements necessary to keep koi and also has personality. The Japanese influence can be seen in the use of the small black pebbles on the edge, wooden posts, and in the Oriental landscaping. Notice the unique filtration system utilizing whiskey barrels as containers for the filter medium. Because it was difficult to resist buying young koi, the hobbyists highly overstocked this little pond and put a great demand on the filter system. Unfortunately, this small and shallow pond is also vulnerable to predators. Even though it is a small koi pond, it is very unique and has great charm. 

A Professionally Built Koi Pond 
This concrete koi pond is an example of the ultimate professionally built Japanese style koi pond. It is accented with landscaping that would enhance any home. Notice the magnificent waterfall which is designed to allow the water to cascade down a series of steps and provide magnificent aeration and turbulence. The shape is ideal — long and narrow which encourages the fish to exercise. The fish in this pond are of fine quality and have won many awards in koi shows. The touches of Japanese landscape such as black rocks, cement posts, traditional-style cement bridge, and bonsai tree all add to the wonderfully tranquil setting. This pond provides a very healthy environment to raise koi and at the same time provides the aesthetics of a beautiful Japanese garden. 

Multi-Tiered Pond 
This large concrete pond is a tropical, lushly landscaped, multi-tiered pond in Houston, Texas. The different levels allow the owners to separate fish in different sections of the pond. Because of the tri-levels, separate drains were added to each section, all of which lead to the pre-fabricated upflow gravel filter system which keeps the water clear. The huge trees and tropical foliage are beautiful and add natural shade but, also, they add to the maintenance of the pond because of the amount of debris that falls into the water. This pond is home to some outstanding show quality koi and provides a beautiful tropical setting to the home. 

Formal Above Ground Koi Pond 
This easy maintenance garden is crisp and clean and puts the focus on the brick-trimmed concrete koi pond. The waterfall is dramatic and simple with a single impressive sheet dropping from a higher level trough. Because of the raised ledge, a natural seating area is formed. This also affords the viewer a closer vantage point from which to really appreciate the koi. However, it is important to note that these raised ponds tend to have slight temperature fluctuations. We especially like the elongated kidney shape of the pond because this form encourages the fish to swim. 

Large Koi Pond 
This concrete pond resembles a small lake and is a real eye-opener. Located on a large property in Beverly Hills, California, it holds approximately 100,000 gallons of water, large enough for a row boat. Although the size is impressive and the landscaping is impeccable, this pond is difficult to maintain. The depth is only 3 feet and less in some areas, much too shallow for the size of the koi it contains, many over 24 inches in length. The pond is also in full sun with no shade except the little bit provided by the trees. Filament algae is sometimes a problem. Additionally, the flat bottom makes it difficult for fish wastes and vegetation which have fallen in the pond to reach the bottom drains to the filter. For such a large body of water, the water is usually clear except for an occasional algae bloom. The filtration system consists of an in-pond gravel Japanese style Japanese filter, as well as an out-of-pond filter filled with zeolite. Even though this large pond has some drawbacks, the koi grow large and beautiful. 

Indoor-Outdoor Pond 
Some people enjoy the koi so much they want the fish to be a part of the family! An unusual pond allows the fish to swim to an inside viewing area. The opening to the house is sealed with a clear plexiglass that is cut just above the water line. The pond is very contemporary and dramatic. A drawback to having the pond in the house is the moisture problem it creates. Also, there is a small air gap which allows the outdoor temperature to creep into the house. On chilly nights, this is not good. In spite of the drawbacks of this pond, the uniqueness of being able to view and feed the fish from inside the house is something many koi hobbyists envy. There are many other examples of unique koi ponds that allow the fish to be viewed from within the house. We recall a pond with a gazebo complete with a trap door on the floor next to the patio table. You can feed the fish during your dinner. Another indoor-outdoor pond runs under the living room floor which is partially made of plexiglass! Koi hobbyists can go to the extreme to view their fish! 
Public Koi Ponds 
Many public koi ponds delight young and old. This koi pond is in the Ala Moana shopping center in Oahu, Hawaii. Notice the low level of water. This distance between the water and the spectators discourages people, especially children, from touching the koi. This pond is a large rectangular pond with walls that provide seating for the viewers. These types of ponds, also, face the problem of people throwing coins in the water for good luck. Notice the sign near the pond which says “Pennies make us sick.” All in all, these public ponds enhance the beauty of the area and provide happy moments to the patrons. 

Large Public Ponds 
These ponds are usually in cultural areas such as museums, zoos, libraries, and parks. One we especially like is featured at the entrance of the Arboretum in Washington, D.C. The outstanding feature is the beautiful plants. The ingenious aeration for the fish are little spouts of water scattered throughout the very large body of water. This pond is in full sun and was very green when we photographed it. We are not sure if they even had a filter. The fish were visible only if they came to the surface to eat. 

Another Public Pond 
This pond is on a property in Bel Air, California, near the UCLA campus and is maintained by the school. The effective use of rocks, pebbles, waterfalls, plants and fish create a tranquil setting. The plants also contribute to the traditional mood of this pond. Although the pond is too shallow and is in full sun, it is relatively clear due to the excellent filtration system. Feeding this pond is a gigantic, natural looking rock waterfall several yards away. Notice the fish clustering near the edge in hope that the guests will feed them. 

Mud Pond 
The mud pond is the original type of pond used centuries ago in Persia, China, and other countries in the Orient. It is the healthiest environment for the fish because they obtain nutrients from the mud and the plant life. This is the type of pond used for koi breeding and for growing jumbo koi. Generally enormous, sometimes a full acre in size, these ponds are often green all year round. They are so large that the water level is lowered and large seine nets are used to harvest the koi. It is interesting to note that because of the large surface area of these ponds, sometimes no additional aeration is used. 
We have covered some varied and interesting ponds. When designing your pond or water garden for koi, consider all the requirements needed for healthy koi as well as the aesthetic elements for the surrounding area. Koi need a clean and stable environment. Provide enough space to accommodate the collection as they grow or to allow adding koi to the collection. Include adequate water depth to allow for exercise and protection from predators and fluctuating temperatures. Good water quality is essential with filtration and drainage, mechanical and biological. Moving water with the aid of waterfalls and jets encourages the fish to exercise and helps keep the pond clean. Some shade is advisable to help maintain the brilliant colors of the fish. If these guidelines are followed, your pond will give you magical moments and unlimited enjoyment. 

Bob and Pam Spindola are Water Gardening's Koi Keeping Editors. They own Varsity Pond Supplies in Santa Ana, California, and can be reached at 714-544-2326 or by fax at 714-544-5415.