Compatible Tank Mates for Your Goldfish

A comprehensive guide to compatible and non-compatible fish that you can place with goldfish.

Watching your goldfish swimming about in the tank is something all fish owners enjoy.

The relaxing playful fluidity of their coveted pets takes your mind off of most anything.

Can you imagine having that time of enjoyment and peace flogged with your fish trying to pull the fins right off of each other or, worse, have the other as a snack?

Before you bring a new friend home for Goldie, continue on to read about what kind of fish are compatible with your goldfish.

I am worried that my goldfish is lonely. 

Will adding more fish keep him happy?

Will adding more fish keep him happy

Fish DO get lonely and can even become depressed. 

You will hear a lot about the fact that fish are social and thrive in schools of fish.

However, we are going to look at the scientific facts of fish and depression based on research.

Professor Dr. Julian Pittman, with the Department of Biological and Environmental Sciences at Alabama’s Troy University, conducted a study on fish and depression.

He published findings from his research in “The rights and wrongs of zebrafish: Behavioral phenotyping of zebrafish.” Using a zebrafish, he discovered that fish can become depressed based on numerous criteria, with one being loneliness.

can goldfish get depressed

Additionally, Associate Professor Culum Brown, who is a behavioral biologist with the Macquarie University in Sydney, Australia, published findings on depression in fish. 

So, if you may think your goldfish is lonely, chances are, it probably is!

Before you get more fish, consider the following…

Forward-thinking keeps you from putting your goldfish at risk when contemplating whether or not to add other fish to the tank.

are goldfish sociable fish

Goldfish do well with a few friends around, but you should be cautious in selecting those friends.

You can’t add more goldfish all willy nilly just because they are goldfish.

There are two types of goldfish:

  • streamline-bodied 
  • egg-shaped (fancy) 

Never mix the two because streamline-bodied goldfish tend to be bullies towards fancy goldfish. 

difference between streamline-bodied and egg-shaped goldfish

You can safely place fancy goldfish with other varieties of fancy goldfish, and streamline-bodied goldfish with streamline-bodied goldfish. 

Remember, oil and water don’t mix, and neither do fancy (egg-shaped) goldfish and streamline-bodied goldfish!

Is your tank big enough? Will the other fish have the same water temperature needs?

In our minds, lots of fish frolicking around in a tank is a beautiful sight!

However, overcrowding will cause spikes in ammonia, depletion of oxygen in the water, and fatality in your fish.

over crowding fish tank dangerous

Avoid the temptation to put too many fish in one tank.

Also, you must think about the conditions the other fish require to thrive in.

To be able to add them to your goldfish tank, they must also have the same diet and water temperature needs as your goldfish.

The fish to tank ratio to follow is 1” of fish per gallon of water. 

Just like puppies, fish don’t stay little and grow into mature adults. And, of course, their size increases.

If you get your fish young, they are going to grow bigger, so calculate their adult size when you use the fish to tank ratio.

how big do goldfish get

For example, a fully grown adult goldfish will be 8 ½” and bigger.

To have an appropriate tank, you will have 8 ½” (plus) of fish, so you are going to need at least 8 gallons of water just for that one fish.

When you add other fish, you will need to do that same calculation separately for their water requirement (i.e., two 8” fish will require a 16-gallon tank.)

Size of goldfish at maturity:

  • 1 month-old = 1 ½”
  • 3 month-old 3 = ½”
  • 1-year-old = 8 ½”
  • 2+-year-old = 9+“

What dictates compatibility in fish?

Understanding the characteristics of a fish species gives you an idea of their compatibility with your goldfish. 

Understanding the characteristics of a fish

Five key points determine whether or not fish are compatible with one another.

1. Behavior

  • Do they tend to nip at, chase, or bully other fish?
  • Will they cause slower swimming fish (fancy) to have to compete for food?

2. Swimming Speed

  • Slow swimmers (fancy) should not be placed with fast swimmers. Fast swimmers compete for food, nip at and bully slow swimmers.

3. Diet

  • Do they have similar diets? Feeding two different diets to fish in one tank can lead to problems.

4. Water Parameter Requirements

  • Fish with different water temperature needs cannot be placed together.

5. Size

  • What is the size of the fish at maturity? Your tank must be large enough to handle fish without overcrowding.

Fish that are NOT compatible with Goldfish!

Goldfish are typically peace-loving fish, and adding other fish that have aggressive tendencies won’t end well.

A few common fish that should never be placed with any variety of goldfish are:

  • Bettas
  • Cichlids
  • Corydoras
  • Mollies
  • Tetras
  • Plecos (other than Rubbernose, Bristlenose)
are betta fish good with goldfish

Many will argue that koi and goldfish should never be placed together because koi can be dictatorial and may bully the smaller goldfish.

What fish are compatible with Goldfish?

Compatibility of Goldfish Varieties

NEVER place streamline-bodied goldfish with egg-shaped (fancy) goldfish. Why?

  • Streamline-bodied goldfish are fast swimmers, aggressive eaters, and bully slow swimming goldfish (fancy.)
  • Fancy goldfish are slow swimmers, slow eaters, and are delicate and docile.
different types of goldfish

Fancy Goldfish (egg-shaped) are compatible with other fancy varieties.

  • Bubble Eye
  • Butterfly Tail
  • Celestial Eye
  • Fantail
  • Lionhead
  • Oranda
  • Pearlscale
  • Pompom
  • Ranchu
  • Ryukin
  • Telescope Eye
  • Tosakin
  • Veiltail
types of fancy goldfish

Streamline-bodied Goldfish cannot be placed with fancy, but do well with other streamline-bodied goldfish.

  • Common
  • Comet
  • Shubunkin
  • Wakin

Other Fish Species Compatible with Goldfish

We have outlined some common species of fish that you can safely place together with your goldfish.

Their diets are similar to the goldfish (except the plecos, which are algae eaters.)

Other Fish Species Compatible with Goldfish

There may be more species of fish that do well when placed with goldfish; however, it requires a lot of research about the other fish species.

If you are ever in doubt, don’t do it!

A little side note about koi.

Although it’s relatively common to see koi and goldfish together in outdoor ponds, the two should not be combined in a tank environment unless your tank is a minimum of 100 gallons.

Koi grow to enormous sizes and are typically pond fish because of this. 

Species

Characteristics

Barbs

  • Rosy
  • Checkerboard
  • Gold

✅ Fancy goldfish

⛔ Streamline-bodied goldfish

  • Non-aggressive
  • Becomes stressed if not kept in schools of 6+
  • Size: 2-6”
  • Fast swimmers
  • Same diet and water conditions as goldfish

Note: Streamline-bodied goldfish may nip and bully barbs, so it’s best not to place them together.

Danio

  • Zebra

✅ Streamline-bodied goldfish

⛔ Fancy goldfish 

  • Danios are top dwellers and may cause other fish to compete for food. Not ideal to be put with fancy goldfish because of this.
  • Size: 2”
  • Same diet and water conditions as goldfish
  • Fast swimmers

Note: Danios are fast swimmers and cause fancy goldfish to compete for food.

Loaches

  • Butterfly
  • Dojo
  • Hillstream

✅ Streamline-bodied goldfish

⛔ Fancy goldfish

  • Eel-like appearance
  • Non-aggressive
  • Must be kept in a school of other loaches (3+)
  • Size: up to 12”
  • Bottom feeders
  • Same diet and water conditions as goldfish.
  • Great for cleaning algae and leftover food.

Note: Loaches have been known to chase after and nip on fancy goldfish so, it’s best not to place them together.

Japanese Rice Fish

✅ Fancy goldfish

⛔ Streamline-bodied goldfish

  • Quirky little fish with a bubbly personality.
  • Jumping fish, so tank must be kept covered.
  • Size: 1.5”
  • Same diet and water conditions as goldfish.
  • Very hardy.

Note: Some goldfish have been known to eat smaller fish. Because the Japanese Rice Fish  is smaller, monitor your goldfish to see how they do.

Plecos

  • Bristlenose
  • Rubbernose

✅ Fancy goldfish and streamline-bodied goldfish

  • An ideal tankmate for goldfish.
  • Docile and peaceful.
  • Algae eater, which is a big plus for your tank.
  • Size: up to 5”
  • Diet is different from goldfish. Sinking algae wafers and some raw vegetables keep plecos happy.

Note: Do not place any other species of plecos in with goldfish because the other varieties of plecos will compromise your goldfish’s slime coat by sucking on the goldfish.

Platy

✅ Fancy goldfish

⛔ Streamline-bodied goldfish

  • An ideal tankmate for fancy goldfish.
  • Docile and peaceful.
  • Same diet and water conditions as goldfish.
  • Size: up to 3”

Note: Streamline-bodied goldfish have a tendency to nip at platys so, it’s best not to place them together.

Scissortail Rasbora

✅ Fancy goldfish and streamline-bodied goldfish

  • An ideal tank mate for goldfish.
  • Quite peaceful fish that stay to themselves.
  • Top dweller.
  • Should be kept in schools of 6+.
  • Size: up to 5”
  • Same diet and water conditions as goldfish.

Note: Because they are top dwellers, they may cause fancy goldfish to compete for food. 

White Cloud Minnow

✅ Fancy goldfish

⛔ Streamline-bodied goldfish

  • Vibrant little fish
  • Should be kept in schools of 8+
  • Non-aggressive
  • Size 1-1.25”
  • Same diet and water conditions as goldfish

Note: Some goldfish have been known to eat smaller fish. Because the White Cloud Minnow is smaller, monitor your goldfish to see how they do.

BEFORE Adding New Fish to Your Tank

You have probably read time and time again about the importance of having a hospital tank.

how to set up a fish tank for goldfish

If you are planning to add new fish to your goldfish tank, it’s a MUST to have a hospital tank set up and cycled before shopping for new fish.

New fish should be quarantined for at least two weeks before adding them to your goldfish tank. 

This prevents the spread of disease.

We can’t stress enough how vital it is to never add a new fish directly to your goldfish tank without a quarantine period.

Things you will need to set up a hospital tank:

  • 10-gallon tank
  • Filter system
  • Plastic plants, rocks, etc. to provide hiding places
  • Heater
  • Test Kit
  • Water conditioner

How to set up your hospital tank:

  • Set the tank up along with the filter system. The filter system should be on the lowest setting.
  • Add water and use a water conditioner to treat it.
  • Place decor at the bottom of the tank.
  • Transfer a little bio media from your goldfish tank filter into the hospital tank. This introduces media to help cycle the tank.
  • Place the water heater into the tank. Turn it on to reach the recommended water temperature.
  • Test the water parameters daily until it has reached the ideal levels. Once it has, you can safely place your new fish into the hospital tank.
  • When transferring your new fish from the bag (from the pet store) to the hospital tank, do not spill any of the water inside the bag into your tank. This prevents disease from getting into your hospital tank.
  • Keep your new fish quarantined in the hospital tank for two weeks. Continually check the water parameters and monitor the new fish for any signs of disease.
  • After the two-week quarantine period has ended and the new fish look healthy, you can add them to your goldfish tank.
  • Monitor your goldfish and the new fish for any signs of aggression. Sometimes, what we perceive as play in fish can be aggression. How do you know what the difference is? Aggression includes nipping at other fish, chasing them from other areas in the tank, and exhibiting a butting behavior towards other fish.

Be Selective in Choosing Friends for Your Goldfish

Choosing new tankmates for your goldfish is quite like finding friends for your child.

how to choose the perfect goldfish

You have to be careful and make sure they are going to get along.

Having variety in your goldfish tank provides you the joy of watching the different species interact and play. It also keeps your goldfish from being lonely.

Lastly, if in doubt about a new fish to add, listen to your gut!

>