Carp vs Koi: 4 Main Differences Explained

Written by Crystal
Published: September 27, 2022
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Koi is the Japanese word for carp.

During the 19th century, people began capturing vibrantly colored carp in Japan. Years of breeding produced the ornamentally colored fish we now call koi. Along with different colors, these fish have also changed how they spawn and survive.

How do koi fish and common carp compare? Read on to learn all of the differences between carp vs koi.

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Comparing Carp vs Koi

Koi  vs Carp
Koi are a type of carp that are the result of generations of selective breeding.


AppearanceDark brown or gold color
Red-orange rings
Barbells at the corner of their mouth
Long dorsal spined fin
Triangular head shape
Blunt snout
Exotic color combinations
Barbells on each side of the upper jaw
Long serrated dorsal spine
Popular colors: orange, white, bright gold, black
Life CycleFully mature in 2-3 years
Spawn in springtime
Females produce 3 million eggs
Spawn in springtime
Need water temperatures of 64 F to spawn
Fry stay near the water’s surface once hatched
Ecological ImpactDegrading water qualityNo impact in captivity
Wild koi degrade water quality
Range and DistributionNew Zealand, North America, Australia, Asia, Eastern EuropeCaspian, Aral, and Black Seas

Carp vs Koi: Key Differences Explained

The key differences between carp vs koi are their appearance, life cycle, ecological impact, and range and distribution. Common carp have brown gold bodies, while koi fish have exotic color patterns. Common carp usually carry out their life cycle in the wild, whereas koi fish are a popular pet.

Koi fish are carp that have been selectively bred over centuries. Wild koi fish migrate large distances to find the perfect spawning grounds.

Both fish can threaten the environment by stirring up sediments as they forage for food. However, koi fish wouldn’t even exist without the help of human interaction.

You can find large populations of common carp throughout North America, Australia, and New Zealand. There are also native to Asia and Eastern Europe. Koi fish occur naturally in parts of Asia and throughout the Caspian, Black, and Aral Seas.

Keep reading to understand the differences between carp vs koi fully.

Carp vs Koi: Appearance

Japanese Koi in a pond.
Koi fish are an ornamental fish species.


Common carp are cute (unlike bighead carp). Once fully mature, they have a dark brown or gold color. Their fins have a reddish-orange hue. They have scales that cover their entire body and barbells on each side of the mouth. The barbells are cat-like whiskers, similar to the ones on a blue catfish.

Common carp don’t possess a true spine. But they do have a dorsal-spined fin. They also have a triangular head and a blunt snout.

While common carp look common, koi fish look exotic. Koi fish are ornamental and come in various colors and patterns. Some of the most popular color combinations include orange, white, silver, bright gold, and black color patterns. They have a deep body and two barbells on each side of their upper jaw. They also have a serrated (notched) dorsal spine.

Carp vs Koi: Life Cycle

Chinook Salmon fingerlings in a stream. The fry will remain in the freshwater for 12 to 18 months as they feed and grow before returning to the ocean.
Koi fry stay near the water’s surface.

©Kevin Cass/

Common carp fully mature once they reach the length of 30 cm and they’re 2 to 3 years old. When they fully mature, both sexes migrate into shallow wetlands. It’s here that they’ll spawn in the springtime.

Females can carry up to 3 million eggs at a time. When the eggs are released by, they’re immediately fertilized. The fertilized eggs cling to aquatic vegetation. It only takes a week for the eggs to develop and hatch fully.

Since each female can produce several hundreds of fry, it’s easy for carp populations to become superabundant. However, common carp can only thrive in areas that lack native predators.

Alternatively, koi fish eggs hatch in the early springtime when the temperatures are optimal at around 64° f. The fry is susceptible to bacteria and parasites, so researchers are exploring aloe vera as a treatment.

The koi fry stays near the water’s surface before they go through the next stage of their life cycle called Nishikigoi. At this time, they’ll change into a more silvery-colored fish and grow scales on their backs.

As the koi fish mature, it’ll enter a stage called Sanke. Finally, when koi fish fully mature, they become Kohaku. They can live 15 to 20 years in captivity (or older, one koi reportedly reached 226 years of age!) and tend to max out at 12 inches in length.

Their lifespan is similar to common carp in the wild. One of the reasons koi fish have such a long life is how they store fat under their skin. This helps them withstand colder temperatures while also fighting off parasites and disease.

Carp vs Koi: Ecological Impact

Excessive algal blooms make it difficult for other aquatic plants to thrive.

©Jesus Cobaleda/

Even though common carp isn’t considered invasive, they can negatively impact the environment. How they live their lives tends to degrade the water quality around them.

When common carp hunt for food, they stir up a lot of sediments. They also uproot aquatic vegetation and increase the overall water turbidity. Their impact on the water conditions can stimulate excessive algal blooms.

When too many algae are in the water, it’s difficult for aquatic vegetation to get the light it needs. When the other aquatic vegetation doesn’t have enough light, it dies off. This poses a problem to other fish who rely on those plants as a food source. Thousands of hectares of waterfowl habitat are being destroyed by common carp.

Koi fish wouldn’t exist without the help of human interaction. As long as they’re kept out of natural bodies of water, koi fish can make the perfect pet. They’re lovely to own in decorative ponds and can even form bonds with their caretakers.

When koi fish escape or are released into the wild, they can threaten their environment. Areas such as Queensland and New South Wales, Australia, deal with problems from wild koi. Similar to the common carp, koi degrade water quality by stirring up sediments as they forage the substrate (ocean floor).

Carp vs Koi: Range and Distribution

Koi fish are native to the Caspian, Black, and Aral Seas.


You can find sizeable common carp populations in New Zealand, North America, and Australia. They’re native to Asia and Eastern Europe.

Currently, there are also 48 states in the United States with established common carp populations. Some states have more common carp than others. For instance, Minnesota is dealing with the superabundant common carp populations.

Marshes that kill off predatory fish over the winter are a perfect spot for common carp to lay eggs. In places like Lake Minnesota, young carp thrive because there aren’t a lot of panfish populations. When panfish are present, they gobble up carp eggs in larvae rapidly.

Koi fish naturally occur in parts of Asia. Wild koi are native to the fresh bodies of water around the Caspian, Black, and Aral Seas. Unfortunately, there are also invasive koi fish populations plaguing the Australian waterways.

Koi were domesticated back in the 19th century and live throughout the world. They’re a popular addition to decorative ponds all across the globe. Other fish species that go great in ponds include catfish, sturgeons, and high-finned sharks.

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Koi  vs Carp

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About the Author

Crystal is a curious writer who's always looking to learn more. When she's not out in nature, she's writing about it. Animals, plants, survival tips, and more. It'll be exciting to watch this author grow and learn with her along the way.

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