Bio Facts: Koi
Originally found in Central Europe and Asia; koi have been introduced in every continent except Antarctica.
Larger, slower-moving bodies of water with soft sediments but are tolerant and hardy fish that thrive in a wide variety of aquatic habitats.
Common carp can grow to a maximum length of 5 feet (1.5 m) and a maximum weight of over 80 lb (37.3 kg). Dorsal spines (total): 3 - 4; dorsal soft rays (total): 17 - 23; anal spines: 2 - 3; anal soft rays: 5 - 6; vertebrae: 36 - 37. Pharyngeal teeth 1, 1, 3:3, 1,1, robust, molar-like with crown flattened or somewhat furrowed. Scales large and thick. `Wild carp ’ is generally distinguished by its less stocky build. Very variable in form, proportions, squamation, development of fins, and color. Caudal fin with 3 spines and 17-19 rays. Last simple anal ray bony and serrated posteriorly; 4 barbels; 17-20 branched dorsal rays; body grey to bronze.
13 – 20 years (in the wild); 50 years or more (in captivity)
In the wild, they eat water plants, insects, crustaceans (including zooplankton) and benthic worms. In the Zoo, they are fed a scientifically developed, commercially available pelleted fish food.
The common carp is a hardy fish, and koi retain that durability. Koi are cold-water fish, but benefit from being kept in the 59-77°F (15-25°C) range. They do not tolerate long cold winter temperatures well as their immune system ‘turns off’ below 50°F (10°C). Koi ponds are usually 3’ (1 m) or more of depth in areas of the world that become warm during the summer, whereas in areas that have harsher winters, ponds generally have a minimum depth of 4’6” (1.5 m).
The koi is an omnivorous fish and will often eat a wide variety of foods. Koi food is designed not only to be nutritionally balanced, but also to float so as to encourage them to come to the surface. When they are eating, it is possible to check koi for parasites and ulcers. Koi will recognize the person feeding them and gather around them at feeding times. They can be trained to take food from one’s hand. In the winter, their digestive system slows nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Their appetite will not come back until the water becomes warm in the spring. When the temperature drops below 50°F (10 °C), feeding, particularly with protein, is halted or the food can go rancid in their stomach, causing sickness.
Like most fish, koi reproduce through spawning. A female lays a vast number of eggs (300,000 or more) and one or more males fertilize them. Nurturing the resulting offspring (referred to as “fry”) is a tricky and tedious job, usually done only by professionals. Although a koi breeder may carefully select the parents they wish based on their desired characteristics, the resulting fry will nonetheless exhibit a wide range of color and quality. Unlike cattle, purebred dogs, or more relevantly, goldfish, the large majority of these offspring, even from the best champion-grade koi, will be unacceptable as nishikigoi (no interesting colors) or are even genetically defective.
The semi-randomized result of the koi’s reproductive process has both advantages and disadvantages. While it requires diligent oversight to narrow down the favorable result that the breeder wants, it also makes possible the development of new colorations within relatively few generations.
The koi’s bright colors put it at a severe disadvantage against predators; a white-skinned Kohaku is a visual dinner bell against the dark green of a pond. Herons, kingfishers, raccoons, cats, foxes, badgers and hedgehogs are all capable of emptying a pond of its fish. A well-designed outdoor pond will have areas too deep for herons to stand in, overhangs high enough above the water that mammals can’t reach in, and shade trees overhead to block the view of aerial passers-by. It may prove necessary to string nets or wires above the surface. A pond usually includes a pump and filtration system to keep the water clear, making them easier to see.
Niigata Prefecture (新潟県) is a prefecture of Japan located on Honshū Island on the coast of the Sea of Japan. The capital is the city of Niigata. The name Niigata literally means “New Lagoon”. It is famous as the original home of the ornamental carp known as koi, and the best-quality koi are still considered to come from the farms of Niigata.
Koi, or more specifically nishikigoi, which literally means “brocaded carp”, are ornamental domesticated varieties of the common carp (Cyprinus carpio) that are commonly kept for decorative purposes in outdoor ponds and water gardens. They are sometimes also called Japanese carp.
Koi were developed from common carp in Japan in the 1820s, and are still very popular there as they are a symbol of love and friendship. Many different colors and color patterns have since been developed; common colors include white, black, red, yellow, blue, and cream. The most popular category of koi is the Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties. Today, there are over 100 named color varieties.
Goldfish were developed in China more than a thousand years ago by selectively breeding Prussian carp for color mutations. By the Song Dynasty (960 – 1279), yellow, orange, white and red-and-white colorations had been developed.
Goldfish (Carassius auratus) and Prussian carp (Carassius gibelio) are now considered different species. Goldfish were introduced to Japan in the 16th century and to Europe in the 17th century. Koi on the other hand, were developed from common carp. Koi are domesticated common carp (Cyprinus carpio) that are culled for color, they are not a different species and will revert to the original coloration within a few generations if allowed to breed freely.
In general, goldfish tend to be smaller than koi, have a greater variety of body shapes, and fin and tail configurations. Koi varieties tend to have a common body shape, but have a greater variety of coloration and color patterns. They also have prominent barbels on the lip. Some goldfish varieties, such as the common goldfish, comet goldfish and shubunkin have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Since goldfish and koi were developed from different species of carp, even though they can interbreed, their offspring are sterile.
Koi can live for centuries. One famous scarlet koi, named “Hanako” (c. 1751 – July 7, 1977) was owned by several individuals, the last of which was Dr. Komei Koshihara. Hanako was reportedly 226 years old upon her death. Her age was determined by removing one of her scales and examining it extensively in 1966. She is (to date) the longest-lived koi ever recorded.
Common carp is the number one fish of aquaculture. The annual tonnage of common carp, not to mention the other cyprinids, produced in China alone exceeds the weight of all other fish, such as trout and salmon, produced by aquaculture world wide.
It is an extremely popular fish with anglers in many parts of Europe, and their popularity as quarry is slowly increasing among anglers in the United States (though destroyed as pests in many areas).Carp are also popular with spear and bow fisherman.
Carp is also eaten in many parts of the world both when caught from the wild and raised in aquaculture. In Germany, Austria, the Czech Republic, Slovakia, Hungary, Croatia and Poland, carp is a traditional part of a Christmas Eve dinner.
Carp are mixed with other common fish to make gefilte fish, popular in Jewish cuisine. The Romans farmed carp and this pond culture continued through the monasteries of Europe and to this day. In China, and soon after in Japan, carp farming took place as early as the Yayoi Period (ca. 300 B.C - 300 A.D.).
The word ‘koi’ comes from Japanese, simply meaning “carp.” It includes both the dull grey fish and the brightly colored varieties. What are known as ‘koi’ in English are referred to more specifically as ‘nishikigoi’ in Japan (literally meaning ‘brocaded carp’). In Japanese, ‘koi’ is a homophone for another word that means ‘affection or love’ and have come to symbolize love and friendship. An example of this is given in a short story by Mukoda Kuniko, “Koi-san”. Koi tattoos have also become a popular trend in North America.
Koi have been accidentally or deliberately released into the wild on every continent except Antarctica. They quickly revert to the natural coloration of common carp within a few generations. In many areas, they are considered an invasive species and pests.
The unique method of feeding employed by common carp has important ecological implications. The feeding of carp has been shown to decimate macrophytes and decrease overall water quality. Carp reduce macrophyte biomass in three ways; 1) Bioturbation - carp often uproot aquatic macrophytes when feeding, 2) Direct Consumption - carp have been known to feed on tubers and young shoots, 3) Indirectly by increasing turbidity which in turn limits the available sunlight. Carp have been shown to decrease water quality by increasing turbidity and increasing the amount of nutrients in the water column. Carp increase turbidity directly by resuspending sediments and indirectly by increasing nutrients thus increasing phytoplankton in the water column. Carp increase nutrients in the water column in two ways. A minimal amount of nutrients are introduced into the water column directly by sediment resuspension but the majority of carp introduced nutrients are acquired by excretion. Carp act as “nutrient pumps” when they consume the nutrient rich benthic sediments and then excrete those nutrients back into the water column in a form that is available to other organisms. This tendency to cause a general decay in water quality and the high fecundity of the carp has caused them to be generally regarded as a nuisance.
Jacksonville Zoo History:
The Jacksonville Zoo currently manages two separate groups of koi. One group of is currently in our lemur exhibit moat. We do not have good records as to when these koi first started arriving, but we have narrowed the timeframe down to sometime on or between 1956 and 1962. Although for several decades this group was not considered part of our animal inventory, we do know that they did successfully breed here at least once in the early 1990s.
The newer and larger koi group is the one in the new koi pool in the Asian Bamboo Garden (opened March 2009). These koi are all new to JZG and started arriving in late 2007. This group has already successfully bred here, too.