Why Do Clown Fish Rub on Anemones- 4 Reasons

If you got clownfish on your own, you must’ve noticed that they tend to keep closer to sea anemones. The way a clownfish keeps contact with anemones, like swimming through them, rubbing on one, and so on, that’s really noticeable.

You will wonder why clownfish prefer the closeness of sea anemones to all other creatures, even another clownfish! However, a curious mind might feel the urge to know the process of these specific two pairing up in detail. 

Clownfish rub on anemones prior to start living in the anemone. This rub thickens the mucus layer of the clownfish and it becomes invulnerable to anemone’s nematocysts. They get to know each other during the period so that they can build their symbiotic relationship while keeping each other safe from predators, sharing nutrients, etc. 

Read this post and explore the ways clownfish interact with anemones. Feel free to amuse yourself!

4 Reasons for Clown Fish Rubbing on Anemones-A Thorough Analysis

There are more than a thousand species of anemones available in the ocean. Whatsoever, this is to inform you that, out of those thousands only somewhat around 10 species are found coexisting with the available 26 tropical clownfish species. They show a symbiotic relationship between them – which is a mutually beneficial status. 

The very basic reason for a clownfish to rub on a sea anemone is that the fish is trying to identify the probability of hosting the sea anemone for a long and full time. During the rub, they have this shared microbiome (sharing of bacteria) and other competency adjustments. 

They do this as a part of the pairing process. It’s more like getting to know each other. In a way, the anemone learns to treat the clownfish not as a threat. When you find a clownfish rubbing on a sea anemone, they are more likely to move in for their symbiotic relationship.

However, apart from these concepts, there are also some reciprocal beneficial factors why clownfish rub themselves on anemones that have been found so far including mutual protection from potential threats, the clownfish’s ability to tolerate the nematocysts of anemones, a fair exchange of nutrients, an increased flow of oxygen for the anemones, etc. There might be some other benefits that are yet to be discovered. 

1. Mutual Protection from Potential Threats

Mutual Protection from Potential Threats

Both the parties (sea anemones and clownfish) act in a way of protecting each other from potential threats. It’s not a one-way rather reciprocal thing. Sometimes sea creatures like sea stars, butterflyfish, and snails try to eat anemones as a protein source, and on the other hand, a clownfish might be attacked by any aggressive or larger creature.

However, in both situations, one party plays the savior role for the other. Let’s get the details.

Clownfish Helping Anemones

Anemones are designed to protect themselves on their own with their tentacles. It’s most likely if any creature gets in contact with the anemone, the victim will sting the attacker with the tentacles.

It will paralyze the attacker and anemone will consume the attacker as food. Anemone even might sting a human if someone happens to graze the surface. Though most of the anemones are not harmful to human beings, some extremely toxic ones (like Actinodendron arboreum, Phyllodiscus semoni and Stichodactyla spp, etc) might be.

Even after that, some creatures (sea stars, butterflyfish, or snails) try to consume anemones. Here, if the anemone isn’t healthy enough or has damaged tentacles, it becomes impossible to defend.

But, if a clown fish appears to be having a home there, the attacker will retreat. The clownfish have an amazingly territorial which is hard to believe. However big the intruder is, clownfish will fight for their home. And that is appreciated by the anemone.

Anemones Sheltering Clownfish

Even if the clownfish act as highly territorial, apart from their great tendency of aggression towards intruders, they are weaker and more vulnerable against larger creatures. Moreover, who feels like fighting every day for their lives? Thus, clownfish find their preferable shelter provider, sea anemones.

Since anemones have tentacles on them, they appear as a great shelter for clownfish. Whenever any aggressive fish attempts to attack the clownfish or any dangerous fish appears around the anemone, the clownfish can hide among the tentacles. But the intruder won’t be able to do the same.

Whereas anemones won’t sting the clownfish, they’ll sting the other intruders. With the fear of getting stung and poisoned, the attacker will leave the clownfish alone.

Therefore, clownfish prefer to stay around anemones to protect themselves and their eggs. Hiding in the anemone is the answer to how clownfish camouflage! 

2. Clownfish’s Immunity Against Anemone’s Tentacles

Being living creatures, anemones do have their own defense mechanism to protect themselves from any attacker. They use their tentacles to serve the purpose. They also use them to paralyze and hunt their food.

These tentacles have nematocysts (stingers similar to harpoons). They have poison on them. Whenever any threat or food appears near anemones, they sting them to either scare them off or to hunt them.

However, very first of all, anemones don’t consider clownfish either a threat or food. Moreover, even if anemones try to sting clownfish which is a very rare and distinct incident, clownfish have this safety measure called – the mucus layer.

Apparently, other fishes also are born with this layer. But to keep things in favor of the ecosystem, nature has blessed clownfish with a thicker mucus layer than others. The layer is three to four times compared to others. 

Hence, a study by the Royal Society shows that, whenever a clownfish keeps close to an anemone, it appears with a thicker mucus layer than usual. And this mucus layer protects clownfish from any kind of hostile sting from an anemone.

The rub thickens the layer gradually. And that answers the question – ‘why don’t clownfish get stung by sea anemones?’.

3. A Fair of Exchange of Nutrients

Clownfish provide sea anemones with nutrients since the presence of a clownfish sometimes also scares away a potential food for the anemone. Clownfish do it by providing fertilizer.

They live in the anemone and as a living habit, they defecate surrounding the anemone. And this biowaste is used by the anemone as fertilizer to get necessary nutrients.

On the other hand, clownfish depend upon anemones for beneficial bacteria. They have this shared microbiome (exchange of bacteria).

Since there is well grown seaweed around an anemone, clownfish may happily eat them. Though the seaweed around an anemone tends to grow in plenty, it might hinder the anemone from getting the required sunlight, water flow, etc. By eating them, the clownfish helps out the anemone as well.

Again, clownfish have another way of getting nutrients from anemones. They consume the leftover food from the anemone. Sometimes, they also nibble on the tentacles of the hosted anemone. But that doesn’t find that threatening for the shared microbiome.

4. An Increased Flow of Oxygen for Anemones

Though the anemones appear with their tentacles, they are not much capable of controlling the water flow around them. They depend on the natural water flow for food, nutrients, oxygen, and whatsoever.

And during the night, when there’s less oxygen in the water, they breathe chokingly. But not with the presence of a clownfish.

In a study by Nanette Chadwick from Auburn University in Alabama, it has been observed that, when an anemone is kept with its host clownfish together, they tend to breathe 40 percent extra oxygen at night than being kept apart!

The basic concept is that clownfish swim through the tentacles while opening them up and making way for more water flow which means oxygen and on.

As a matter of fact, it was believed among marine scientists that clownfish mostly sleep during the night. But not when they host an anemone.

Clownfish are seen as more active than anyone could even imagine during the night when they are aligned with an anemone. They even perform their ‘dance’ (wedging or a u-turn movement) under an anemone.

What’s the exact reason is yet to be studied. Are there any chemicals from the anemone that lead the clownfish to do so? Or it’s just nothing but a symbiotic relationship? Or are there any other unknown purposes to date that are being served with the movement?

What is the Best Anemone for Clownfish?

The Best Anemones for Clownfish

As previously mentioned, only around 10 species of anemone and 26 species of clownfish can get along, you can’t expect to grow them well in any combination. Therefore, focus on the following aspects while choosing an anemone for your clownfish:

  • Don’t go for any faded or light colors. Avoid white.
  • Keep aware of the mouth size. The smaller, the better.
  • Grab an anemone with a smooth foot area. (no tears)
  • Check the health. (whether it reacts while picking)
  • Tentacles shouldn’t be too thin or too short.

Let me suggest you two specific types: Saddle anemone and Bubble tip anemone. They appear with the highest rate of survival with clownfish.

Saddle anemone is found on reefs (shallow water) among seagrasses. They have sandy and soft bottoms. Their depth range is 13 to 130 feet.

The other one (bubble tip) is a common part of saltwater fish tanks. Having a variety of colors, they are a great match for true percula and maroon clownfish. They grow up to 30 centimeters. They are found near Fiji and Singapore.

While picking an anemone, take the attachment along with it. If it’s attached to a rock, don’t detach it unless it’s an ultimate necessity.

Frequently Asked Questions (FAQs)

How do clownfish protect themselves from predators?

Clownfish are extremely territorial. They fight for their homes with utmost aggression. But fighting for life can’t be a daily job and the aggression falls short before larger creatures. When they face such predators, they tend to hide in the anemone that they are living in while camouflaging themselves among the tentacles. 

How do anemones kill their prey?

Being living and carnivorous things, anemones need to eat on themselves. Therefore they are adorned with tentacles. These tentacles have nematocysts. And those are poisonous. Whenever any food appears in reach of an anemone, it stings the prey with the nematocysts. The prey becomes poisoned and paralyzed. During this process, anemone uses actinoporins to kill the prey. 

Do anemones sting clownfish?

Simply the answer is no. Because of their symbiotic relationship and shared microbiome, anemone refrains from stinging the hosting clownfish. Though sometimes clownfish may nibble on the tentacles, due to the thick mucus layer of a clownfish, they become invulnerable to the nematocysts of the tentacles. 

Can clownfish survive without an anemone?

They can! But they do better with the company of an anemone. Though there are habitual changes in a clownfish while staying in an anemone, they are not permanent. And mostly a clownfish needs an anemone for security and comfort. If you have any other aquatic creature or rock cave or any such place for a clownfish to hide, an anemone isn’t a must.


Since the rub of clownfish on an anemone leads to a symbiotic relationship, the phase works as an ice breaking time between the clownfish and the anemone. Throughout the phase, they know each other and prepare to build a symbiotic relationship. As a result, none of them find the other as a source of food.

Because of the thick mucus layer of clownfish, any rare sting from the anemone can’t even do a thing. They support each other in terms of nutrient sharing, and bacteria sharing as well.

As there are different species, clownfish rub on anemones to build a mutual understanding. So worry not about the act rather focus on the types!

Howard Parker

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