Can Goldfish Live with Koi Fish? (How EXPERTS Manage!)

Can Goldfish Live with Koi Fish

If you are a fish keeper, you need to be aware of choosing the appropriate tankmates.

May you be confused in thinking that can goldfish live with koi fish? It is possible to put them together if you add these two fish in an ample space with proper circumstances. 

In this article, you’ll acknowledge some facts about koi fish and gold fish’s living habits. 

Can Goldfish Live with Koi Fish?

A question may arise for a beginner fish owner, can goldfish live with koi fish? Goldfish and koi fish are pond fish, and their care requirements are almost identical. Therefore, avoid fancy goldfish, and pick the same-sized fish. They can stay together for a while since koi fish may increase in length.

You need to be conscious of putting them in the same tank. Otherwise, koi fish may eat the goldfish.

Set Up a Tank for Goldfish and Koi Fish: 10 Steps Guide

You can put goldfish and koi fish together if you know how to set up the tank.

Setting up the tank is easy for any experienced level fish keeper. But it is difficult if you’re a beginner fish keeper as sometimes koi fish chase the goldfish, and they make the water cloudy frequently. 

What you’ll need–

  • Tank 
  • Fish size
  • Gravel
  • Driftwood
  • Plants
  • Filter
  • Water
  • ph
  • Temperature
  • Food

Setting up process–

Step 1: Choose a big tank

Koi fish and goldfish are pond fish. Koi fish is huge, so it requires large spaces. 

If you put them in a tank, it may look overcrowded, and it might be the cause of koi fish’s death. Koi fish and goldfish need a large pond, which looks better from the top than the side.

For keeping a koi, you need to choose a minimum of 60 gallons tank; for goldfish, you need at least 30 gallons tank.

You can put them in a 150-gallon tank under proper circumstances. In a 150-gallon tank, they can survive well. 

Step 2: Fish size matters

The size of goldfish and koi fish is not the same. Koi fish grow between 24 to 36 inches in length. It grows up to 3ft long.

In bigger tanks and outdoor ponds, goldfish grow up to 6 inches. But wild goldfish grow about 14 inches, which is hard to find and requires extra care to improve their length. It grows a maximum of 1ft long.

The length of koi fish is bigger, and the strength and swimming speed are also good. Koi fish target small fish if the small fish is easy to fit in its mouth. The goldfish, which have big long flowy fins, are suitable for koi fish.

Make sure to avoid small goldfish; otherwise, koi fish might eat the small goldfish. 

Keep the small koi fish with the same-sized goldfish until the koi fish grows—size matters to avoid any fight and attack.

Step 3: Put some gravel.

Collect some fine gravel and put them on the bottom of the large tank. Make sure to spread the gravel throughout the tank as substrate.

Use gravel in a container to filter the water.

Step 4: Make hideouts with driftwoods.

Use driftwoods in the middle of the tank to give a beautiful natural look for taking a rest and handling any stressful situation for the fish.

Make sure to put the smooth driftwoods and don’t overcrowd the tank with driftwoods.

Step 5: Add some plants

You can plant and make the tank natural. But koi don’t get along with pond plants. 

Usually, koi mess with plants as their mouth has barbells to rummage the dirt and food.

You can add plants if the koi is small in size. For example, water hyacinth, water smartweed, and water lettuce can be put in the koi fish and goldfish tank.

Step 6: Use a good filter

Add a three-in-one powerhead submersible water pump and filter to the tank. Make sure to use a filter and air pump to provide oxygen. The filter will provide crystal clear water.

Both koi fish and goldfish make the water dirty easily. But koi need better water quality and aeration; otherwise, the koi would die off in a controlled pond where there is no opportunity to provide any filtration and aeration.

Goldfish cannot quickly die. They can tolerate the poor water quality. 

Step 7: Add the clean water

Use a pipe to add clean water. Use chlorine in the water before putting the fish in the tank. This chlorine will develop bacteria which will control the ammonia level and keep the water clean.

Before adding goldfish to the tank, float the plastic bag of goldfish in the tank to match the temperature and ph level.

Make sure to use 30-50% of shopkeepers’ water to avoid any problems.

Change the water twice a week and clean it with a gravel vacuum every two or three days.

Step 8: Temperature

Use a heater to control the temperature. 

Koi fish and goldfish both prefer a cool environment of 68 to 74 degrees Fahrenheit for goldfish and 59 to 77 degrees Fahrenheit for koi fish.

Harsh winter can kill the koi fish so maintain the temperature in the winter. 

Keep an eye on the tank whether the water is getting warm. Warm water can’t hold oxygen like cold water, which is essential for goldfish and koi fish.

Step 9: Ph level

You need to maintain the water parameters to ensure a healthy environment. For example, goldfish and koi fish require an average of 6- 8.4 ph value.

Step 10: Food habits

Make sure to provide them with adequate healthy foods.  

To keep your goldfish active, feed them less quality food. Goldfish are omnivores, and overfeeding may cause many diseases.

Koi also love to eat vegetables, but they eat plants and other small fish if the fish fits in their mouth.

Ensure to provide more food in the summer and spring seasons to strengthen them. They eat less food in fall and winter.

Watch the video to learn how to set up a tank for koi fish and goldfish.

Why Can’t Goldfish Live with Koi Fish?

Koi fish can’t keep up with incompatible fish. So, please ensure the selected goldfish are not inconsistent with koi fish; otherwise, it may create problems. Goldfish can’t live with koi fish for the following reasons –

  • Avoid fancy goldfish as they are small in size, and their swimming speed is slower than other goldfish varieties.
  • Don’t put both fish if the tank size or pond size is small
  • If the goldfish is capable of fitting into a koi fish’s mouth.
  • If there are no arrangements for the air pump and water filtration. 

Goldfish Versus Koi Fish

There are so many opposite behaviours that koi fish and goldfish have.


Koi fish are larger and more colourful. It has a unique colour and cool patterns.

Goldfish are comparatively smaller, and the colour pattern is not as impressive as koi fish.


Koi fish live longer. They live 15-40 years on average.

Goldfish live 10-20 years on average. 


Koi fish is an intelligent species. Following their feeding schedule, they can quickly identify their feeder. Koi fish are knowledgeable and also the most expensive fish as well.

Goldfish are not intelligent as koi fish and are cheaper.


Make sure to don’t put mature goldfish and koi fish in a tank that will breed. 

If goldfish start to breed, they will breed a lot of small fries, which may overcrowd the tank. Koi fish also may eat those tiny goldfish fries, which are unable to survive.

Koi fish and goldfish may mate with each other if you put them together. They can develop a sterile fry. So it’s better to separate goldfish and koi fish if they are about to breed.

Which Tankmates Do You Need to Choose and Avoid for Koi Fish?

You need to choose compatible tank mates with similar water conditions, temperament, and food requirements. Otherwise, they may fight, spoil the environment, and develop diseases.

You can choose the following fish as the tank mate of koi fish–

Common goldfish, pleco, silver shark, kissing gourami, comet goldfish, tinfoil barb fish, giant gourami, shubunkin goldfish, and iridescent shark.

You can’t keep the incompatible tankmates with your koi fish. They are –

Danio, guppies, minnows, and fancy goldfish.

Which Tankmates Do You Need to Choose and Avoid for Goldfish?

Goldfish are sensitive species,  so choose non-aggressive fish to keep with goldfish.

You need to choose–

Silver dollar fish, freshwater loach, tetra fish, guppy fish, Koi carp, Tropical dwarf cichlid, silver shark, balloon molly, zebra fish, angel fish, Senegal fish, Dwarf Gourami, Pleco fish, Honey gourami, Swordtail fish, and African cichlid.

You need to avoid the following fish for goldfish–

Molly fish, tiger barb fish, rosy barb fish, oscar fish, parrot fish, and a group of angel fish. 


Now you know that can goldfish live with koi fish. Make it successful! In this article, you’ll discover all the facts–

  • Both goldfish and koi fish are pond fish 
  • Their care requirements are almost the same. 
  •  Avoid fancy goldfish, and make sure to pick the same-sized fish.
  • They can stay together for a while since koi fish may increase in length

Therefore, you can easily identify why your fish are troubling to live along and how they can be put together.

Frequently Asked Questions

Are your koi aggressive to goldfish?

Koi is aggressive to some specific fish. They are aggressive to fancy goldfish as they are small in size. But they get along with comet goldfish, common goldfish, and shubunkin goldfish.

Are your dirty koi fish?

Koi is well-known for its impressive colour combinations, but it makes the water dirty easily. 

It releases waste, and their mouth messes the water quality quickly.

Which one is hardier, koi or goldfish?

Goldfish are considered the most challenging fish as they release too much waste in the water and require oxygen.

Will your big koi eat little koi?

Definitely yes. Koi fish are considered omnivores. However, they may eat the small koi fish if it gets well in their mouth.

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