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"How many clownfish can I have in my aquarium" is a question that I am often asked. Just last night, I was asked by a customer if they could "add a few more" clownfish to their30 gallon aquarium. Since the customer already had one clownfish I had to inform them that they could only add one more clownfish.

The simple answer to how many clownfish that you can have in your aquarium is 1 or 2. For a while, you may be able to keep 3 or 4 clownfish together, but eventually, 2 of the clowns will pair off and start to pick on the rest of the clowns. A related question is how do you tell what sex clownfish are. In general, female clownfish are biggest, males are smaller, and very small clownfish are gender neutral.

Clownfish start off life as a neutral sex and change sex depending on what is needed in the surrounding area. If no male clownfish is present in the group, the dominant juvenile fish will transform into a male. If there is no female, the male will become a female, and a juvenile will become a male. Once a clownfish becomes a female it can not turn back into a male.

Once the clownfish pair up in your aquarium they tend to quarrel with any other clownfish in an effort to protect their area. It is natural instinct for clownfish to want to spawn to carry on the species. As a result, they are very territorial towards other fish, including clownfish, that come into their area. I have had my hand attacked and bitten many times by female clownfish protecting their territories.

This territorial nature will eventually lead to the demise of any other clownfish that you try to keep in the same aquarium with a pair. As a result, unless you have a very large aquarium, you should only keep 1 or 2 clownfish per aquarium. If you want multiple clownfish, it is best to add to small clowns at the same time.

If you already have a clownfish and would like to add another be sure that your new clownfish is smaller than the one that you have. You don't want to have 2 female clownfish in the same aquarium because they will fight, and choosing a smaller clownfish will help to ensure that you don't add another female.

It is also best to not mix clownfish species in the same tank. The different species see each other as competitors and will fight until the losing clownfish is removed or is eliminated. Also, it is necessary to use caution when trying to keep a pair of Maroon Clownfish. Maroon clowns are notoriously aggressive, and it can be very tricky to make maroon Clownfish pairs. Look for a later post on how to pair up Maroon Clownfish.

To summarize, only keep 1 or 2 clownfish per aquarium. If you already have a clownfish and would like another one, make sure that you add a smaller clownfish of the same species.

John Crosby

Aquatic Escapes Aquariums