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Are Clownfish Aggressive And How To Deal With Aggressive Clownfish!

After the initial spike in the popularity of clownfish after the release of Finding Nemo, a huge number of people have decided to add a clownfish to their aquariums with clownfish now being of the most common fish to keep.

With so many people being new to keeping clownfish, it’s not surprising that we see so many people reaching out with various questions on how they should be keeping their clownfish in their aquariums.

One of the more frequently asked questions that we have noticed people asking time and time again is based on if clownfish are aggressive or not.

We see a large number of people reaching out about the aggression levels of clownfish as well as how you are able to reduce their aggression levels so we have decided to publish our own article going over clownfish aggression levels.

With there being a range of similar questions about clownfish aggression asked from the community each month, we have decided to add a table of contents to our article below.

It should make it as quick and easy as possible for you to navigate our article with ease.

Are Clownfish Aggressive?

Clownfish are naturally aggressive and territorial due to their instinct being to establish themselves as the dominant male in an area as quickly as possible.

Although this instinct is not as strong in some clownfish as it is in others, the majority of clownfish will nip and chase other fish in your tank.

This is due to all clownfish being born male and the hormone they require to morph into a female only being released by their thyroid once the clownfish has established itself as the dominant male in an area.

This is why clownfish will often display high amounts of aggression to each other and other fish in your aquarium from a young age.

Thankfully, once a dominant clownfish has been established for your aquarium and the other males have submitted, the aggression does tend to reduce.

Although the dominant clownfish may still display aggression to some of the other fish species in the tank, they will usually be few displays of aggression, especially toward the other clownfish that have already submitted.

How To Deal With Aggressive Clownfish!

Unfortunately, the only way to deal with clownfish aggression in some cases is to separate your clownfish from each other as they can fish to the death if neither clownfish will submit to the other.

An overly aggressive clownfish can also be extremely aggressive to some of the other fish species in your aquarium too so removal is often the only real option.

Although it is not guaranteed, we have seen a number of people report that they have been able to reduce the aggression in their clownfish by upgrading them to a larger aquarium.

This is due to the more territory being available for your clownfish to live in, the less likely they are to fight but in hyper-aggressive clownfish, this may not help in the slightest so you have to keep that in mind.

The minimum recommended tank size for a clownfish is 20 gallons with the standard recommendation of add an additional 10 gallons for each additional clownfish.

Although this is sound advice for the average clownfish, it is simply not enough for a hyper-aggressive clownfish and we would recommend a minimum of 50 gallons if you intend to keep any other fish from any species in the tank with an aggressive clownfish to try and reduce aggression.

How Long To Separate Aggressive Clownfish!

You may have to separate two hyper aggressive clownfish indefinitely if neither of them are willing to submit to the other.

Although it is rare that you will end up with two hyper aggressive clownfish, they can end up fishing to the death if you leave them in the same tank for long enough.

We have a dedicated article going over how to stop two clownfish fighting each other that may be able to help you if you are having problems with two clownfish being aggressive to each other.

You also have to think of the other fish species in your tank too as hyper aggressive clownfish will focus on fighting each other but they will also nip and chase other fish species that get to close to what they perceive as their territory.

This is why it is relatively common for some fish keepers who keep clownfish to have to go out and purchase a decent 20 gallon tank for their clownfish to keep them separate from their other fish.

The majority of the time, one clownfish will be able to establish itself as the dominant clownfish in the tank though and the other clownfish will submit to it.

What Is The Least Aggressive Clownfish?

Most people consider the occelaris clownfish to be one of the least aggressive clownfish species available.

This tends to work out well for most people as Nemo from the Finding Nemo movie is a occelaris clownfish and it is the particular species that most people want to add to their tanks.

In addition to being classed as a semi-aggressive fish rather than an outright aggressive fish, the supply of occelaris clownfish has grown with demand making them one of the cheaper clownfish options if you order your fish online.

This is why we usually recommend any of our readers who want to add a clownfish to their aquarium opt to add a occelaris rather than any other type of clownfish.

Please note though, just because the occelaris clownfish is considered to be one of the least aggressive clownfish species, it does not mean that they are not aggressive.

They can still show signs of aggression to other fish in your tank as well as fight with other clownfish in the tank, it just tends to be rarer than with some of the other clownfish species.

What Is The Most Aggressive Clownfish?

The maroon clownfish is usually considered to be the most aggressive clownfish although there are a number of other clownfish species that also border on being hyper-aggressive and territorial too.

You really should do plenty of research into any species of clownfish that you are wanting to add to your tank due to there being so many that are aggressive.

The various types of hyper-aggressive clownfish will not only fight each other for dominance but they can also go off looking for fights with other fish species too.

Depending on the other types of fish that you have in your aquarium, this can end up causing you a number of different problems.

It can be common that some maroon clownfish as well as the other hyper aggressive clownfish variants will simply have to be put into their own tank due to being so aggressive to other fish.

Although it is a shame when this happens, it may end up being the only option available to you as some maroon clownfish will just try to fish everything in your tank.


That brings our article going over if clownfish are aggressive as well as how you are also able to deal with the aggression of clownfish to end. We hope that we have been able to help you understand how you may be able to keep the aggression levels of your clownfish under control but depending on the specific type of clownfish that you have as well as their aggression levels, you may end up having to just put the clownfish in a separate tank.