Koi and goldfish are both part of the carp family of fish. Some people may keep goldfish as household pets, and others may maintain koi ponds, a landscape fixture that has become synonymous with natural tranquility and serenity. What are the differences between these two types of fish? This article will help explain.
Definitions
Goldfish are a type of domesticated carp, and one of the most common aquarium fish. Goldfish originate from the Prussian carp, and were first developed in China. There are over 300 breeds of goldfish, and most of these breeds have originated in China. Goldfish can be colored red, orange, black, or white, and fully mature goldfish are typically 8 – 12 inches in length, with a lifespan of up to 25 years. The ideal temperature in which to keep goldfish is 68 – 72 degrees Fahrenheit, or 20 – 22 degrees Celsius. Varieties, pictured above, include the common goldfish, top, the celestial eye goldfish, middle, and the comet-tailed goldfish, bottom. A distinguishing feature of goldfish are their double-finned tails.
Koi varieties (click to enlarge)
Koi are also a type of domesticated carp that were developed from the common carp in Japan. Koi have a multitude of colors and patterns, such as those pictured above, and have base colors of white, blue, orange, yellow, red, and black. They can be up to three or four feet in length when fully mature, and have a lifespan averaging 20 – 25 years, though in some cases koi have lived for over one hundred years. A distinguishing feature of koi are their barbels, a whisker-like organ on each side of the mouth. A koi’s barbels are pictured below. An interesting fact is that “koi” in Japanese is a homophone (a word that sounds that same as another but has a different meaning) for another word meaning “affection” or “love”, and for this reason, koi are often symbols of caring, friendship, and love in Japan.
Comparison chart
| Koi | Goldfish |
| Bigger in size. | Smaller in size. |
| Longer lifespan. | Shorter lifespan. |
| More patterns and color variations. | Often just a solid color. |
| Barbels and a single-finned tail. | No barbels and a double-finned tail. |
| Developed from common carp in Japan. | Developed from Prussian carp in China. |
Koi vs Goldfish
The main differences between koi and goldfish are:
- Size
- Lifespan
- Patterns and colors.
- Barbels and fins on tail.
- Origin of the fish.
Koi are larger than goldfish, with mature adult sizes of 18 inches to four feet. The size of adult goldfish are anywhere from 8 – 12 inches.
Koi have an average life-span of 20 – 25 years, though some koi have lived for over a hundred years. Goldfish have an average life-span of about 10 years, though some have lived for about 30 years.
Goldfish have little variations in pattern, and are usually just a solid color. Goldfish can be red, white, yellow, orange, or black. Koi on the other hand can have a variety of patterns, with a solid base color of red, white, orange, yellow, blue, or black.
Koi have barbels on either side of their mouths. Barbels look somewhat similar to a cat’s whiskers and are a sensory organ. Goldfish do not have barbels on their mouths. However, goldfish have double-finned tails where koi have single-finned tails.
Goldfish were developed through selective breeding of the Prussian carp, and originated in China, whereas koi were developed through breeding the common carp, originating in Japan.