With the recent rise in Koi Carp, it can be difficult to tell them apart from other types of fish. Here are some methods for telling these two different animals apart during a visit with your local aquarium or pond.

Koi Carp are a type of fish that is much different from the common goldfish. They have long, flowing fins and they can grow to be quite large. If you’re not sure how to tell them apart, it’s easy: Koi Carp have red eyes and goldfish don’t.

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Koi are a lovely ornamental fish that are becoming more popular in home aquariums. When compared to the typical carp, they might seem quite similar to people who are unfamiliar with the species.

Did you know, though, that the koi fish is derived from the carp? Furthermore, this is a rather recent phenomenon. It’s also worth noting that, despite their similar looks and characteristics, koi fish are not carp.

Here is a detailed explanation of the distinctions between carp and koi.

Body Form

One of the main things that help to tell the carp apart from koi is their Body Form. The fact of the matter is that the two are quite different in terms of their overall shape.

The body of a carp, for example, is slightly compressed and taller (not longer) than that of a koi. The belly of the carp grows the most, while the koi fish grows a little longer.

Through selective breeding, the koi fish has developed an almost torpedo-like Body Form where they have a narrow head and tail with a thicker midsection. This is the biggest difference between carp and koi fish.


As much as their Body Form makes them different, perhaps the most important and obvious difference between the carp and koi fish is in their coloring.

Carp have a deeper, more neutral hue. They have a golden or dark brown hue that fades to a lighter tone as they go closer to their belly and fins.

Koi fish, on the other hand, are brilliant and colorful, with a vast spectrum of patterns and hues. You’ve probably seen koi fish in a variety of hues, including yellow, red, orange, blue, black, and white.

This is one of the reasons they are so popular in home aquariums.

Their brilliant colors make them a superb ornamental addition to any home aquarium, making them a noticeable addition. It’s also one of the reasons they’re more costly than their carp cousins.


The fins of common carp and koi fish are one of their most distinguishing features. It may not be the first thing that stands out about the two to the untrained eye, but it may be just as telling as anything else.

The dorsal fin of the carp is elongated, and each of its fins has a distinct spine. This isn’t always obvious, but there is a significant difference from koi that have lost their spines.

This is what gives their fins an almost majestic and flowing appearance, especially in butterfly koi.

In every way, the carp seems to be more “simple,” but the koi is more bright, flowing, and distinctive.


Despite their colorful and attractive appearance, koi fish may grow to be much larger than their carp cousins.

The koi fish may reach lengths of up to 24 inches by 28 inches. The carp, on the other hand, may grow to be between 15 and 27 inches long.

Carp, on the other hand, may grow to be pretty huge in terms of weight. Carp may grow to be rather enormous, with the world’s largest carp reaching 105 pounds. “Big Girl,” the world’s biggest koi, weights just 91 pounds.

The difference isn’t significant, and the carp might seem bigger while being shorter in length.


The scales are the final major distinction between the two species. Leather carp and leather koi are koi and carp that are completely devoid of scales.

The scales of a koi fish are more curled, regular, and smaller than those of a typical carp when they do have them.

Their scales are also far brighter and more appealing than those of ordinary carp. As a result, it’s not unusual to find koi in aesthetic tanks and aquariums.

Predators attack koi in their natural habitat. It’s impossible for them to stay away from their prey because of their stunning, brilliant hues. Their fins, although lovely and flowing, render them far less capable swimmers than carp.

Furthermore, their bent, smaller scales do not provide them with the same level of protection as the carp’s. It’s one of the reasons they’re so widely accessible as a decorative item.

The ecosystems that they pervade are the final major distinction between them. Carp are a tougher fish that can be found almost everywhere on the planet.

Koi perform best in ponds that have been specially designed to showcase them rather than in open water (remember, they are weak swimmers and have no camouflage).

Purchasing Koi Fish

While carp aren’t extremely widespread in tanks and ponds across the globe, koi are. Koi are nearly a trophy fish more than anything else because of their beautiful coloration and impressive fins.

If you’ve ever looked for koi fish, you know that depending on what you’re searching for, they may be rather costly. For example, the show’s grand champion was sold for $1.8 million during the 2017 All Japan Koi Show, making it the most expensive koi fish ever.

However, why are koi fish so costly? The major reason is that koi breeding is so common.

Rice farmers in Japan started cultivating koi as early as the 1700s. Koi fish were picked for their unique patterns and colors, similar to how dogs are bred for their unique characteristics.

In certain locations, collecting koi fish is a serious pastime, and both collectors and breeders take the process extremely seriously. The huge koi fish exhibits, as well as the fairly hefty price tag of $1.8 million for a single koi fish, are proof of this.

So, why do koi fish cost so much? They turn out to have a few characteristics that make them incredibly collectible and expensive.


Japanese breeders started looking at koi bloodlines to find the most vibrantly colored, beautifully aesthetic koi. The wild carp, one of the koi’s progenitors, has a deeper hue that is less appealing to koi, despite the fact that it helps them live in the wild.

A prize koi will usually show the polar opposite of those genes. They have colors that are wild, brilliant, and as beautiful as it gets, rather than subdued hues that are better for survival. The more vibrant their hues are, the higher the price they will likely command.

In their skin, koi will have six distinct color cells: yellow, red, white, black, blue, or a metallic shine. Bloodlines with a lot of red cells growing in large patches with white bodies will be the most prized of kois.

The colors white and red are very prominent in Japanese culture. They are not just the colors of the Japanese flag, but they also symbolize purity and pleasure.

This is one of the main reasons why white and red koi fish are so prized for their breeding ability.


Prize koi have certain standards that have to be met among collectors and hobbyists. They have to be of a certain Body Form, size, and health standard, including the way in which they move through the water.

However, the most distinguishing feature of koi fish is their ability to stand out in terms of appearance. The finest koi will have a pleasing combination of patterns and colors, however this might vary depending on variation.

Koi with greater red patches on their backs, lighter koi with blue spots, and koi that seem to be fully metallic gold are the three hues that the majority of koi lovers will search for.

While colors and aesthetics are really essential, there are certain hues that will just not look well. The cells that retain the fish’s color will be found at various depths in its skin.

Some will be found deep under the skin, while others will be found near the surface. These characteristics may have a significant influence on the koi fish’s brightness and visual attractiveness.


Did you know that there are over 120 different types of koi fish in the world today? Not only that, but in a single birthing session, a single koi may give birth to hundreds of thousands of young fish.

As a result, in order to get the greatest koi, the breeder may end up having several million young koi on their hands.

As these fish develop, the breeders will likely conduct a couple rounds of choices depending on their criteria. The reductions may be drastic: from three million infants to about 15,000 to 20,000 in the first year, then down to approximately a thousand the following year.

Koi fish may live up to nine years, which is how long the aforementioned grand champion koi lived before being sold. Breeders, understandably, are investing more on their koi setups and inventories.

What Does a Koi Cost on Average?

When it comes to pond-quality koi, the price range is often determined by a number of factors. On a regular basis, you may get them for as little as $10 or $100. It is entirely dependent on the size of the koi fish.

Show-quality fish, on the other hand, may be a true money pit. The greatest exhibition koi in the world have been bred specifically for that reason.

This also indicates that their bloodlines are quite stable, which means that their major color qualities and attributes are rather predictable.

Spending hundreds of dollars on a single koi is all too usual among dedicated koi collectors. Most serious koi investors will often breed their own koi fish in the hopes of producing a grand champion contender.

What Are the Most Expensive Koi?

The red and white fish, as mentioned in earlier parts, are particularly emotive and essential to Japanese collectors. But, given that there are more collectors worldwide than Japanese, what are some of the other color kinds that command the highest prices?

Light blue-spotted koi and all-metallic gold koi are also quite popular (and pricey).

These three color varieties are often the most valued and tend to dominate the show circuit, regularly winning almost every major category in these competitions.

Is It Possible to Estimate the Age of a Koi Fish?

When the koi fish reach maturity, it becomes much simpler to distinguish between them in terms of age.

In general, the length of a koi fish is the most important element in establishing its age. They are three years old when they reach a length of 10 inches or more and are considered mature.

Any koi fish that is less than 10 inches in length is termed a juvenile. Before being sold, most champion koi fish would have grown for seven to nine years, making them considerably bigger and more mature than their younger peers.

Koi are very attractive and colorful, making them ideal for collecting. They may be seen swimming elegantly in ponds and even in bigger home aquariums.

If you want a competitive koi fish, expect to spend a lot of money. Only the strongest (and richest) koi fish will survive the fierce struggle.

Koi Carp are a type of fish that can be distinguished from other types of carp. They have goldfish-like scales and a rounder body shape. Goldfish are also similar to koi, but they do not have the same markings or colors. Reference: goldfish vs koi vs carp.

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