How Many Clownfish in a Tank?

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Are you thinking about setting up a clownfish aquarium? Then, you’re probably wondering if your tank is large enough to house your future Nemos.

Clownfish can be a little space-demanding, so you won’t be able to keep them in a small tank. But if you have a medium-sized aquarium, rest assured you can keep at least one clownfish.

How many fish could you fit in your setup? That depends on your total aquarium size. Keep reading to learn more about clownfish space requirements.

In this article, you’ll discover the minimum tank size and the ideal number of clownfish you can keep together. Let’s get right into it!

How Many Clownfish Can You Keep in a Tank?

Clownfish are medium-sized, growing up to 4 inches in length. They’re also active swimmers and quite territorial.

You’ll need a roomy tank to keep multiple specimens and other fish species. As a general rule, one clownfish needs at least 20 gallons worth of space.

Any additional clownfish beyond that requires an extra 10 gallons.

You can use this formula to calculate the number of clownfish for any aquarium size. Or check the table below, where I’ve already calculated it for you!

Here’s a short and sweet rundown of the numbers:

Tank Size Number of Clownfish
10-gallon 0
20-gallon 1
30-gallon 2
40-gallon 3
55-gallon 4
75-gallon 6
100-gallon 9
125-gallon 11


One important note here! Clownfish love anemones in the tank. If you plan to add one of those, you need a 50-gallon tank minimum.

Anemones are space-intensive and must be spaced 9 inches apart.

Even if you’re only planning to keep one or two clownfish, you’ll need a medium-to-large aquarium to add live anemones.

Do Clownfish Need to be in Groups?

Clownfish are social fish that like hanging out with their peers. In the wild, these fish live in groups and establish social hierarchies, with a dominant female leading the group.

They can do the same in the tank, so watching them together is interesting. That said, clownfish aren’t a schooling species and don’t need to be in groups. Even in the wild, clownfish can fend for themselves.

Although having multiple clownfish together keeps them active and entertained, clownfish can also live alone.

This is quite rare, as most fish naturally live in shoals. Such fish tend to get stressed and timid when kept alone.

But the clownfish can live on its own comfortably. It’s good news if you have a small tank and can only keep one fish!

How Many Clownfish Can You Keep Together?

Theoretically, you can keep several clownfish together if your aquarium is large enough. However, it’s strongly advised that you only keep two clownfish at most. Juvenile clownfish get along well in the aquarium.

But once the fish reach maturity and start breeding, you’ll face problems.

Clownfish do best in pairs, and they mate for life. Once your fish reach sexual maturity and establish a pair, the other fish in the tank become targets of bullying.

It’s even worse if you have two mated pairs in the same tank because then you have multiple female clownfish. Female clownfish are aggressive to one another and often fight to their deaths.

Of course, these are just general rules. Keeping a pair of clownfish will make your life easier and is safer for the fish.

But you can still safely keep three or more clownfish together if you know what you’re doing.

If you’re planning to keep multiple clownfish together, remember the following tips:

  • Provide enough aquarium space for the number of clownfish you want (see table above).
  • Add the clownfish to the tank at the same time; don’t bring in any newcomers!
  • Only keep one female in the group to prevent aggression.
  • Add aquarium plants and hiding spaces where the bullied fish can retreat.

Are Clownfish Happier in Pairs?

This is an often-debated topic among aquarists. Some swear by the clownfish duo, while others prefer keeping their fish alone to minimize aggression.           

It’s highly likely, though, that clownfish would be better off living in pairs. Remember— enrichment is the most important thing to keep happy and healthy pets!

In this case, living in a pair provides clownfish with important behavioral enrichment.

“What is behavioral enrichment,” you ask? According to Wikipedia, “Behavioral enrichment is an animal husbandry principle that seeks to enhance the quality of captive animal care by providing the environmental stimuli necessary for optimal psychological and physiological well-being.”

In the wild, clownfish occur either in groups or in pairs. Although the fish can also live alone, interacting with other fish is most natural for them.

Creating the most natural living conditions in the aquarium will keep your clownfish active and entertained.

Interacting with other fish also provides mental stimulation and psychological benefits. It makes sense if you think about it. After all, clownfish are social creatures.

What is the Minimum Tank Size for Two Clownfish?

Are you thinking about keeping a pair of clownfish? Then, you must ensure the fish have enough room in the tank.

Remember, these fish are active and rapid swimmers. They need a large, open swimming space. As for the bare minimum tank size, you’ll need a 30-gallon tank for two regular-sized clownfish.

Of course, more room is always better. You may want to add anemone to your tank in the future, and these also need plenty of room.

Many aquarists include live anemones in their aquariums as part of clownfish enrichment.

Clownfish love these sea creatures and use them for sleeping and hiding. An anemone might need 20-50 gallons of space, depending on its size and species.

Can You Have One Clownfish in a Tank?

Absolutely! Clownfish are social animals but can also live alone. As long as you have a 20-gallon aquarium minimum, you can safely keep one clownfish.

Many aquarists do this without problems. However, your clownfish won’t be as energetic and active on its own.

Even fish get bored when there’s nothing to do! So, add more aquarium decorations to give your clownfish plenty of playtime opportunities.

You can also add other fish species alongside your clownfish. Medium-sized or small fish with peaceful temperaments can make good tankmates for your lone clownfish.

Purple Firefish and Bumblebee Gobies, in particular, need just 10 gallons of aquarium space, so you don’t need a lot of room for them. Other compatible but more space-demanding fish include the Royal Gramma, Green Chromis, and Pajama Cardinal.


As a general rule, you need at least 20 gallons for the first clownfish in your tank and an additional 10 gallons per each extra clownfish beyond that.

This means that clownfish are only suitable for medium to large aquariums. You’ll need at least a 30-gallon tank to keep a pair of clownfish.

If you have a 20-gallon tank, you can keep just one clownfish. However, this fish thrives in a pair. Having two clownfish provides opportunities for play and social interaction. Keeping more than two clownfish together is uncommon.

Mated clownfish tend to be aggressive towards other clownfish in the aquarium. Avoid keeping groups of clownfish if you want to minimize aggressive behavior.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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