Koi Fishkeeping

Koi fish have been fascinating creatures to keep for many years and can display some wonderful colourations. They can fetch large prices for the quality strains and there are many Koi fish keepers who regard them as their prized possessions. Unfortunately this has led to a small black market taking place and some keepers have even had their fish disappear from their ponds due to the profits that can be made from selling these fish.

The name “Koi” is actually an abbreviation for “nishikigoi” which can be translated into English as “brocaded carp”. Koi fish are actually direct descendants of the common carp but through selective breeding are now classed as a species in their own right. They are not classed as aquarium fish but are classed as ornamental pond fish; they are relatively hardy and live for many years growing into large specimens as they mature. Originally the carp were only to be found in Europe and Asia but since they were domesticated, populations of these fish are to be found worldwide as they can adapt very well to different climates and particularly in Japan, they have become one of their favourite fish.

It was in the 1820’s that the carp were selectively bred for their colouration and in the early 20th century this practice became more and more widespread.

Although the Koi and the goldfish were both descended from the Prussian carp, there are visible differences between the two species that are obvious even to novice fish keepers. Koi carp always have the same body shape and finnage, with goldfish the body shape and finnage will vary greatly, this is more pronounced with the selectively bred fancy goldfish, Koi fish also posses barbels near their mouths. These are not always visible when they are juveniles but soon become apparent as they mature. Koi and goldfish have been known to interbreed, this is quite common when they are housed in ponds together but the offspring are always infertile and a new strain from mixed parents could never be established.

Koi fish have several requirements for a long life even though they are classed as hardy fish and meeting these requirements when your Koi fish pond is first designed will save a lot of heartache at a later stage.

They are a very active species and not suited for small ponds, often Koi fish ponds can be 1000’s of gallons with the minimum for keeping these fish at least 1500 gallons for a limited number of specimens.

They also require water movement in the fish pond; often you will see Koi fish ponds with the corners that are slightly rounded, these are to prevent any dead spots and to keep the water flowing freely. If a pond liner is being used in your fish pond rather than cemented walls then make sure that any of the corners are well tucked and tidy as this can also affect the water flow in the fish pond if they are irregular.

Winter months are always the worst time of the year for any pond fish, allowing fish pond to freeze over can cause problems for the fish and if the pond is not deep enough, the Koi fish will have to tolerate water temperatures outside of their comfort zone. All Koi fish ponds should be at least 4 feet deep, this allows the fish to go to the bottom of the fish pond where the temperature will be slightly higher than the upper levels, a layer of ice over the pond can trap toxic gases which will affect the health of the fish, a good investment has to be a pond de-icer, this does not keep all of the fish pond ice free but it will leave one area free and all of the gases can escape through this.

Feeding Koi carp may seem a bit daunting when you first research this subject but to simplify matters, their eating habits change throughout the year and this is mostly dependant on the water temperature of the fish pond. During the winter months the Koi carp are largely inactive and will not require feeding unless they are showing signs of being hungry, at this time of year the foods should be Koi pellets that are high in carbohydrates. Vegetable matter can also be supplied by offering them lettuce or even cabbage.

As the temperature increases in the spring, the water temperature should rise and feedings should gradually be increased to at least once per day, the foods at this time of year should consist of Koi pellets that have a protein level of approximately 35%, this should be varied with fruit and vegetables.

The temperature will continue to rise up to the summer months so the feeds should gradually increase until they are at their most active, the optimum water temperatures for the Koi carp is between 72-80 deg F. Now the Koi will be constantly hungry and very active, their metabolism will be at its highest and high protein foods will now be required by the fish. Fruits, vegetables and meaty foods such as shrimp will need to be offered as will colour enhancing foods, these are normally marked on the Koi pellet containers. Often during the summer months it may be required to feed the fish 3-4 times per day, they should never have digestive problems as they can digest their food very quickly, hence the constant hunger. I have seen keepers throw a whole cabbage into the pond and the Koi carp have attacked it as a shoal of Piranhas would with a kill.

As the water temperatures decrease into the autumn months, the feeds should also decrease and the amount of protein foods should also be lowered gradually as you return to a carbohydrate diet in the winter months.

If the fish are fed correctly through the year there should be no problems with them surviving the summer months ready for the start of a new year.

When using commercial Koi pellet food, always make sure that they are well in their best before dates that will be marked on the containers, any foods that are even approaching the best before dates should not be fed to the Koi as the nutritional value will have decreased dramatically.