Last Updated: 2/9/09

Quick Information
Description and Varieties
Butterfly Koi and Longfin Koi
Ghost Koi
Koi Eating From Your Hand
Telling Goldfish and Koi Apart and Interbreeding

Common names: Koi, Japanese Carp, Japanese Colored Carp, Nishikigoi
Scientific/Latin name: Cyprinus carpio
Maximum length: 2 to 4 feet
Colors: Red, white, "blue," black, orange, yellow, metallics, and lots more
Temperature preference: 50 to 75 degrees F but can survive 33 to 100 degrees F for short periods of time
pH preference: 7 to 8
Hardness preference: Moderate
Salinity preference: 1 Tablespoon per 5 to 20 gallons
Compatibility: Very good, may eat small animals inadvertently with plant material or fish food
Life span: 50 to 150 years or more
Ease of keeping: Easy if large pond with adequate filtration provided
Ease of breeding: Easy if large pond provided and eggs removed from parents and other fish

Cyprinus carpio, koi, or Japanese colored carp can grow to four feet in length. They can live over a hundred years. According to a thread on the rec.ponds newsgroup, one of the oldest documented koi was 226 years old in Japan (Her name was Hanako, and she weighed 20 pounds and was 30 inches long. She died in Japan in 1977. They counted the annual rings on her scales to tell her age. That is not a fully accurate method of aging koi though.). Koi can lay thousands of eggs at a time. Most often, they only grow to a few feet long. Older koi can grow beyond 30 inches. They grow throughout their lives but may stop breeding later in life. Only the fry are suitable for tank life. In a pond, the only suitable life for such large and elegant fish, they require at least a few hundred gallons a piece, depending on their size at the time. Outside, they also need a few feet below maximum ice depth to overwinter. Koi experts say to have at least 1000 gallons for the first koi and 100+ gallons for each additional koi. Koi come in reds, whites, yellows, blacks, and blues (not true blue) of all combinations. They can be dull or shiny, short-finned or longfinned. There are hundreds of Japanese names for the various patterns, finnage, scales, etc. Three of the most common types of koi are the Kohaku (red and white, the most well known variety), Showa (red, white, and lots of black), and Sanke (red, white, and a little black). Judging and breeding koi is a large business in Japan, China, and parts of the US.

Longfinned koi or butterfly koi are part koi and part Indonesian carp and are not recognized in judging yet in many areas. They have long, flowing fins and come in most colors of ordinary koi. My butterfly koi seem to be a bit smaller and hardier than ordinary koi. Yet, butterfly koi are reputed to be faster growing and larger than regular koi. Apparently longfin koi and butterfly koi may be different types of koi. One source says that butterfly koi have long, flowing fins with feathery edges whereas longfin koi have fins not all that longer than regular koi. Longfin koi may also be called dragon carp. Butterfly and longfin koi grow fast and have long fins and sometimes long barbels and sometimes even pom-poms on their nostrils. One koi keeper says that butterfly koi have forked mouth barbs over 7 to 8 inches in length unlike longfin koi. There is much confusion between butterfly and longfin.

Ghost koi are a mix of a platinum ogon koi and a common river carp. They have a shadow or skull-shaped patch on their backs and/or head over "wild colored" skin. These dark, "ugly" koi were developed in the UK and are more hardy than ordinary koi. The name is rarely used outside of the UK.

Koi can learn to eat from your hand. First, feed them as normal but keep your hand as close as they will allow while feeding. Try about a foot from the water to start. Then, each day, move your hand closer to the water. After a while, try having your hand in the water near the food. Then, put the food in your hand and into the water. Slowly release the food. Soon, the koi should eat food released from your hand. Finally, feed them directly from your hand. This is all information from other koi keepers since I have never tried it as I am too busy to enjoy my ponds (I work all week at a "job" and spend all weekend taking care of the animals, aquariums, and ponds which is much harder work).

Koi have barbels under their mouths. Goldfish do not. The two species can interbreed producing presumed sterile offspring. Their offspring often have barbels but may not. All hybrid fish who had genetics testing in one test had barbels. In addition to the barbels, goldfish and koi have different body shapes. It is hard to explain but if you look at photos of goldfish and koi enough, you will just know. I have oftentimes been asked if fry found in a pond or tank are goldfish or koi. In most cases, it is more likely that they are goldfish because goldfish are more apt to spawn. Newborn goldfish are blah/black/brown for months (the exceptions are shubunkins and calico fantail goldfish) before developing color whereas newborn koi soon develop some colors akin to their parents within a few weeks. Barbels should also be obvious on koi fry within a month or two.

Cross breeding of koi and goldfish normally only occurs if there are a lot of one species and only one or two of the other. For example, if there were a lone adult female koi with a lot of male goldfish, she might spawn with them. Koi will spawn with koi if they have the option, and goldfish with spawn with goldfish. If both spawn at the same time, there is a slight chance that sperm from one species might penetrate the egg of the other species. But, if a lot of sperm from both species is present, it is usually the sperm from the same species as the egg that will fertilize it.

Kathy sent these photos of goldfish on 9/1/06. What caught my attention is that she did not know what they were. She has many koi and butterfly koi and put in some shubunkins (calico goldfish) about 10 years ago. These fish appear to be goldfish. But, if the only goldfish were shubunkins, that is what they should be. They do not look exactly as goldfish should though. They seem to have some koi-like qualities. I am wondering if they could be the rare hybrids of koi and goldfish. What do you think? The fish that most looks koi-like to me in body shape is the bottom right fish in the last photo. The fish definitely have more than shubunkin in them. The male yellow fish has a partial hood (like an oranda) as well.
Fish, fish, fish, fish, and fish

On my goldfish breeding page:
Telling Goldfish Fry from Koi Fry

Go to koi care page two.

Return to the main koi page.

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