Aquarium Accessories

Can Koi Fish and Goldfish Breed Together?

can koi and and goldfish breed together

If you are trying to find the answer to the question ‘Can koi fish and goldfish breed together? Well, we’ve got you covered. Yes, koi and goldfish can breed together as both are a type of carp fish. They can lay eggs and breed with each other, especially when kept together in the same tank or pond.

These fish are quite rare.

A lucky few have seen them pop up at their local fish store from time to time, but for the most part they are difficult to get a hold of. It would certainly be a fun experiment for a breeder to try making this and make it more widely available for those looking for more unusual scale types. Before we dive into how koi and goldfish breed together, it helps to understand more about both.

Are koi and goldfish the same thing?

We answer this question with a plausible, “No!”. Although they look alike with characteristics that differ in their body shapes, they are not the same type of fish. They both originated from the carp family, but the type of carp they came from sets them apart.

Let’s see what sets these two fish apart!

What do the offspring of a koi-goldfish look like?

There are a few characteristics to look for when trying to identify a goldfish hybrid.

  • A goldfish/koi hybrid may have a pair of barbels or sometimes it doesn’t have barbels at all.
  • It is sterile. Although physically intact, it cannot reproduce.
  • It is between the size of a koi fish and a goldfish.
  • It usually has more scales on the lateral line than the goldfish but less than the koi. Most goldfish have 25–31 lateral line scales while some are between 32–41.
  • It has a more rounded fin shape than the common goldfish.
  • Its tail is not V-shaped like that of a goldfish – it can look almost like the fins of a single-tailed goldfish.
  • It can show sensory organs above the eyes and nostrils (which look like small white dots in neat lines).
  • Some report thicker caudal stalks in their hybrids than goldfish.

There is a myth that koi and goldfish hybrids are brown in color and that is how you can tell they are hybrids. Indeed, all goldfish fry are brown until they are old enough to acquire their true color.

This usually happens around 3-4 months of life of the fish. The colouration of their offspring depends on their parent gene. Of course, other factors also affect coloration, but it is rare for a goldfish to remain brown throughout its life and contrary to the points described above, it is not a characteristic of a hybrid.

Example Koi-Comet (Goldfish) Hybrid

It is a typical hybrid between koi and goldfish.

  • Hybrids are sterile and cannot breed
  • The hybrids I’ve experienced grow to 12″ including the tail and some as long as 15″
  • They seem tougher than the koi and can take to low water quality like goldfish
  • Not sure about their lifespan (goldfish are around 10, some are 60+)
  • They also do not attack plants like koi do to plants
  • Some people report that hybrids have small barbels at the corners of their mouths but the ones I’ve seen don’t

With qualities like these, I’m surprised they aren’t the more popular pond fish and bred for commercial sale.

I have seen many backyard ponds over 500 gallons in size and hybrids would be a great fish for those types of ponds. You should also try adding plants as well. Hybrids get bigger compared to goldfish, but not as huge as any and will not tear up plants.

Difference Between Koi and Goldfish

Koi fish
Originated from
  • Common Carp
Physical Features
  • Size 36″
Distinguishing features
  • 2 sets of barbels near the mouth
  • More variety of colors
  • Colors are vibrant
Body shape
  • Common size
  • Round nose
  • Slender-elliptical body
  • 25-35 Years
  • Environment
  • Fish-to-water ratio: 4″ per 100 gallons
  • Requires a large body of water with a minimum depth of 36″
  • Eats a lot resulting in more fish waste
  • Bottom rummager (barbels on lips help foraging and finding food)
  • Once a year
  • Friendly but will eat small things such as small fish.
Originated from
  • Prussian carp
Physical Features
  • Size 6-10″
Distinguishing features
  • Less variation of colors
  • color vibrancy limited to a few varieties
  • body shape
  • Egg shaped and streamlined body
  • blunt nose
  • rounder body
  • 5-10 years
  • Environment
  • Fish-to-water ratio: 1″ per 10 gallons
  • Lives in tank environment or small pond
  • Eats a lot resulting in more fish waste
  • Feeds mainly on the surface or in the middle of the tank
  • Twice a year
  • Friendly

How to breed koi and goldfish together

Warm pond water encourages spawning. Unless you are constantly monitoring your pond, you will never know when spawning occurs. An important indicator of spawning is a foam-like film on the surface of your pond water.

So, are you interested in breeding koi more goldfish? Let’s take a look at an easy DIY breeding setup and system.

Easy DIY Koi-Goldfish Breeding

The spawning season usually occurs when the water temperature rises during the summer. Plan ahead and get everything done before your fish is spawned.

  1. Prepare a separate tank for the eggs
  • Install a filter system.
  • Cover your ponds so that birds do not lay eggs on your daphnia and dragonflies and other insects.
  • Fill with water and let it sit for a few weeks until algae form.
  • Put daphnia in the water. Daphnia are basically water fleas. They will provide an endless source of food for your frys after they’ve hatch.
  • From this point forward you will need to feed the daphnia every 4 days.
  • Spraying active dry yeast over the surface of the water will keep your daphnia fed and happy.
  • Daphnia reproduces at an exponential rate, so you never have to worry about refilling.
  1. Place either a spawning mop or egg media in your fish pond to capture the eggs.
  • Wait and see
  1. A foam-like film will suddenly envelop the water, and a strong fishy odor may be present, then its time to check the pond for eggs.
  • Transfer the eggs to your pool.
  • Eggs will lay 5-7 days after laying.
  1. Care for the fry
  • Make sure your pool cover stays on. If not covered the birds will feast on your fry.
  • Test your water parameters regularly. Pay attention to nitrite and nitrate levels.
  • If you want to include pellets in their diet, you can feed them small pellets once a day.
  • Some experts recommend that you keep the fry separate from the adults for up to a year.

Related Questions

Do koi fish get along with goldfish?

Although they may look alike, they are not the same and usually require different care and attention. If you are considering keeping either (or both) species as pets in the same aquatic environment, you may be wondering, can they survive together and live favourably? Well, the answer is…

Yes, koi and goldfish can coexist peacefully in captivity, provided they are the same size and kept in a very large tank or outdoor pond. Since both species are peaceful in nature, grow quite large and require ample space to swim, forage and explore, they will do much better if they are not crowded or overpopulated.

Are any fish compatible with goldfish?

Koi fish and goldfish are compatible under the right conditions. If you plan to keep them together in the same tank or pond, they should be the same size otherwise the smaller ones may get eaten!

Both koi and goldfish are docile in nature, but can become aggressive if kept in a very small tank or overpopulated pond. Also, they may eat each other’s eggs or offspring if they are not fed frequently or sufficiently.

Will koi fish and goldfish fight?

Koi and goldfish are less likely to fight – as both are known for their calm demeanor and easy-to-care nature. However, the level of aggression in koi fish will increase especially under stress. Poor water conditions, a crowded tank or pond, lack of food, and egg-laying behavior are all possible culprits of increased stress.

Also, avoid overpopulation of the tank or pond, make sure you are feeding your fish adequately and don’t keep more males than females if possible.

Are koi fish aggressive towards goldfish?

Koi fish are rarely aggressive towards goldfish, unless they are in a cramped aquarium or overpopulated pond. If the water parameters are ‘off’, the koi fish may be stressed. This, in turn, could increase tensions between tank mates.

Do they eat the same food?

Koi fish and goldfish generally eat the same type of food.  The carp species can eat anything. The general rule is that if it can fit in its mouth, it’s fair game! For this reason, you do not want to keep any species with smaller fish or eggs/offspring as they are likely to be eaten.

Do any fish eat goldfish eggs?

Koi fish will eat goldfish eggs – and their own eggs too, for that matter! Koi fish eat a variety of plant- and meat-based foods and are also omnivores. They will also eat other fish if they are small enough to fit in their mouth. Therefore, if you intend to raise koi fish, you should keep them in a large, heavily planted pond that will provide cover for eggs and hatchlings.

Do goldfish eat any fish eggs?

Goldfish, such as koi fish, are omnivores and will eat both plant- and meat-based foods, including other fish eggs. As opportunistic feeders, they forage continuously throughout the day and are on the lookout for food to eat. Their insatiable appetite and desire to eat anything that fits in their mouths (including other fish), make them a threat to newly hatched offspring.

Which fish are compatible with koi fish?

The best tank or pond mates for koi fish are undoubtedly goldfish. The best types include Comet, Orandus and Shubunkin. In addition, barbs, catfish, loaches, and plecos can also live in peace with koi fish. Make sure whatever fish you choose is of similar size and temperament, doesn’t require more care than a koi fish, and won’t compete with koi fish for food.

Which fish are compatible with goldfish?

The most favourable tank or pond mates for goldfish are often koi fish. However, since goldfish are docile and easy to maintain, other species of aquarium fish such as barbs, loaches, plecos, catfish will do well in the same aquatic environment.


If you have a koi pond that has goldfish and koi fish, you now have a very simple way to breed them. So yes, it is possible for koi and goldfish to lay eggs and breed together and they can produce some interesting babies.