What Do Baby Koi Fish Look Like? (Pictures & Video)
by Tory Jon | Last Updated: September 30, 2026
Baby koi rarely look like the bright red, white, orange, and black fish you picture when you think of an adult koi.
Newly hatched koi, called koi fry, are tiny and often have muted colors. Their appearance changes quickly as they grow, and the patterns they eventually develop can take months or even years to fully settle.
Here is what baby koi look like at different stages, when their colors begin to develop, and how to tell young koi from goldfish.
What Do Baby Koi Look Like?
Very young koi have slender bodies, translucent or lightly colored fins, and relatively little of the bold coloration seen in mature fish.
Depending on genetics, young koi may appear gray, brown, yellowish, orange, black, or a mixture of colors. Some begin showing recognizable patches fairly early, while others stay plain-looking much longer.
That makes color a poor way to judge the eventual appearance of a koi.
When koi eggs hatch, the fry are extremely small. For the first few days, they rely on nutrients from their yolk sac. Once they begin swimming and feeding, they eat microscopic organisms and other very small foods.
They become much easier to spot as they grow.
Growth rate varies considerably. Water temperature, food availability, water quality, genetics, and stocking density can all affect how quickly a young koi grows. Rather than expecting every fry to reach a certain length at a certain age, watch for steady growth and healthy development.
You can see more about their growth in our guide to how fast koi grow.
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Video: Koi From Spawning to Young Fish
The video below follows koi through spawning, egg development, hatching, and the growth of the young fish.
Watching the process makes one thing clear: newly hatched koi do not immediately resemble the finished fish sold by koi dealers.
Their appearance changes substantially as they grow.
When Do Baby Koi Get Their Color?
Some koi begin showing recognizable color within the first several weeks, but there is no single age when every koi suddenly develops its adult pattern.
Color development depends heavily on genetics.
A young koi may begin showing orange, red, yellow, white, black, or other pigmentation fairly early, while another fish from the same spawning may remain brown or gray for much longer.
Patterns can also change as the fish grows. Areas of color may expand, fade, sharpen, or shift in appearance as the body gets larger.
That is one reason koi breeders do not judge a spawning only by what the fry look like immediately after hatching. Fish are evaluated repeatedly as they develop, and only a portion of the young fish may eventually display the traits the breeder is looking for.
If you want to compare the patterns that may eventually develop, see our guide to the different types of koi.
Why Do So Many Baby Koi Look Brown or Gray?
A plain-looking baby koi is not necessarily unhealthy or poorly bred.
Young carp naturally tend to have subdued coloration, and ornamental koi have been selectively bred for colors and patterns that become more apparent as the fish develops.
Genetics play the largest role in what a koi eventually looks like. Water quality, nutrition, temperature, and general health can affect development, but they cannot turn a fish without the necessary genetics into a high-quality patterned koi.
So if you discover several brown or gray fry in your koi pond, their appearance alone does not tell you what they will look like several months later.
How Can You Tell a Baby Koi From a Baby Goldfish?
This can be difficult when the fish are very young.
The old advice of identifying them by color alone is unreliable. Young koi can be dark, and young goldfish can remain gray, brown, or dark before developing their later coloration.
A better clue is the barbels around the mouth.
Koi are ornamental common carp and develop small whisker-like barbels near the corners of the mouth. Goldfish do not have barbels.
On extremely small fry, those barbels may be difficult to see. Identification usually becomes easier as the fish grows.
Body shape can provide another clue. Young koi generally develop the longer, more streamlined body associated with carp, while many goldfish develop a deeper body. That distinction can still be difficult with small fish, especially when several varieties are present.
If koi and goldfish share the same pond, there is another complication: the two can hybridize. Their offspring may show characteristics that make identification less obvious than simply looking for a particular color.
For that reason, avoid assuming that every dark baby fish is a goldfish or every colorful one is a koi.
What Should You Feed Baby Koi?
Newly hatched fry are too small to eat ordinary koi pellets.
After the yolk sac is absorbed, very young fry feed on microscopic organisms and other tiny foods available in the water. Breeders raising fry separately often use appropriately sized live or prepared foods as the fish develops.
As their mouths grow, they can gradually move to larger foods.
If koi reproduce naturally in an established pond, some fry may survive by feeding on microorganisms around plants, algae, and other surfaces. Many will also be eaten by adult fish, insects, birds, or other predators.
Anyone intentionally raising a large number of koi fry usually gets better survival by moving eggs or fry to a separate rearing system where food, water quality, and stocking density can be controlled.
Don't Expect Every Baby Koi to Look Like Its Parents
Two attractive adult koi can produce a large number of fry that look very different from either parent.
Koi coloration is the result of selective breeding, and spawning produces considerable genetic variation. Some offspring may develop desirable patterns, some may remain mostly one color, and others may develop markings that change substantially with age.
That variation is normal.
For the backyard pond owner who unexpectedly finds fry, the most interesting part may simply be watching them change. A tiny brown fish that is difficult to notice in spring may look completely different several months later.
What Baby Koi Look Like at a Glance
Young koi usually start life looking much less colorful than mature koi.
They are extremely small after hatching, develop quickly under good conditions, and may begin showing color within the first several weeks. Their final appearance can take much longer to develop.
If you are trying to determine whether young fish are koi or goldfish, do not rely on color alone. As the fish grows, look for the small barbels around a koi's mouth along with its developing body shape and other features.
The changes are part of what makes finding baby koi in a pond so interesting. The fish you see today may look quite different a few months from now.
