How do Clownfish and Anemones Help Each Other?

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If you’ve ever heard of clownfish, you have heard of anemones. These 2 creatures are linked together in what’s called a symbiotic relationship, or mutualism.

The connection between clownfish and anemones is so powerful and standard that you will actually see it used as an example in the definition of symbiosis.

Today, we will look into anemones, and clownfish, and how their relationship affects both organisms. But let’s start with the beginning!

What are Sea Anemones?

Sea anemones are essentially small predators that look like flowers. This look can be deceiving, as it makes them look harmless when they’re anything but.

These creatures belong to the Actiniaria order which makes them related to corals and jellyfish.

They are sometimes very colorful and attractive, which is what earned them the name in the first place. The animal itself is a simple polyp with a foot that attaches itself to a hard surface.

The rest of the body consists of a column-like trunk with a circular mouth at the top, surrounded by an ominous and beautiful ring of tentacles.

The animal’s misleading look works to its benefit, as the coloring, shape, and slow movement in the water often attract fish and other potential prey. When that happens, the anemone will expand its tentacles, envelop the prey, and deliver paralyzing stings via its trademark cnidocytes.

These are defensive and offensive cells that contain a type of neurotoxin meant to either paralyze small prey or deter larger organisms from attacking the anemone.

Sea anemones typically grow up to 4 inches, but many species are smaller. They are also vastly different in shape, size, color, and other metrics, depending on the breed.

Anemones are generally immobile but can also move slowly to other areas if their current region lacks food.

Symbiotic Relationship Between Clownfish and Anemones

Since anemones lack the high mobility of other species, they’ve had to deal with some glaring weaknesses that could’ve ended their species a long time ago.

Fortunately, evolution had other plans, so anemones managed to adapt. One of their evolutionary solutions was forming symbiotic relationships with other organisms, including algae, various crustaceans like crabs and shrimps, and numerous fish species.

The clownfish is one of them. But how does the symbiosis work between these 2 species?

In short, clownfish tend to dwell around anemones and even stroll among their tentacles. Anemones won’t harm the fish because it recognizes the benefits of collaborating with the animal.

The benefits are mutual since clownfish also have something to gain from it. Let’s look into that!

What Anemones Gain:

  • Oxygen – Anemones are immobile for the most part, so they risk not getting enough oxygen to survive. That’s because they have no means of bringing more oxygen around them. They could if they had used photosynthesis, but anemones are not plants, but animals, so that’s out of the question. This is where the clownfish comes in. The fish tends to patrol the area around the anemone and even move through its tentacles in search of food and safety. This will create water movement, increasing the level of oxygen in the region. Anemones will be grateful for that.
  • Personal hygiene – Any immobile animal is subject to parasitic and bacterial accumulation, and clownfish are there to fix that. These fish will patrol and monitor the anemone’s body to scan for parasites and other microorganisms it can consume. This will keep the plant cleaner and the fish always wanting more.

What Clownfish Gain:

  • Security – There’s no doubt that anemones are more than capable of defending themselves, whereas clownfish doesn’t. So, the clownfish will use anemones as a guardian, offering its cleaning services in return.
  • Food – Clownfish cannot survive on cleaning anemones alone, but the extra food they can gather from within its tentacles isn’t worthless either. This will keep the clownfish wanting to return to their favorite anemone for a quick cleaning job whenever possible.

Some types of anemones use a variety of other symbionts to exchange benefits with.

Algae are compatible candidates in this sense, as they also provide anemones with food and oxygen.

Species of anemones like Adamsia and Calliactis even attach to the shells of hermit crabs and some species of snails, allowing them to benefit from their host’s mobility.

Boxer crabs even carry away other, smaller types of anemones on their claws.

The boxer crab will use the anemones as weapons against any potential attacker, while anemones benefit from the crab’s mobility, providing oxygen and more feeding opportunities.

Why are Clownfish Not Stung by Sea Anemones?

It’s unclear why clownfish are not stung by anemones, but I believe the question itself is wrong.

I think that ‘hurt’ is more appropriate there than ‘stung’ because it represents reality more accurately.

Here are some potential explanations regarding the phenomenon:

  • Clownfish are actually stung – Research suggests that some clownfish actually undergo a familiarization process before being accepted by an anemone. This consists of the fish rubbing its body against the anemone’s tentacles which will cause stings due to the anemone’s automatic response. The fish is too large for the anemone to hurt it, so the sting will only cause some local discomfort. The fish repeats the process several times until it eventually becomes impervious to the toxin. So, it’s not that anemones don’t sting clownfish, it’s just that they don’t care anymore.
  • Innate protection – Another theory suggests that clownfish are already immune to anemone poison and don’t need to undergo any accommodation process. This is likely the result of millennia of symbiotic relationships which have changed the fish’s physiology with time. This may not be true for all clownfish-anemone symbiotic relationships but may be true for some, depending on the anemone species itself.
  • Mucus production – Clownfish produce thick mucus which is believed to stop cnidocytes from reaching the skin.
  • Chemical camouflage – Clownfish are known to produce antigens against some species of anemones, possibly all of them. Antigens are substances that camouflage certain organisms against the immune system. So, the immune system will no longer consider the organism a threat. Similarly, anemones will consider clownfish as being part of their own body due to the fish’s antigen camouflage. This will prevent the anemone from employing its cnidocytes, given that it doesn’t see the fish as prey.

All these explanations prove the clownfish’s amazing adaptability, which makes the difference between life and death.

Wild clownfish won’t be able to survive in their natural habitats without the protection they’re getting from anemones.

Do Clownfish Need Anemones in Aquarium?

No, they don’t because the aquarium is a safe environment where the clownfish doesn’t require extra protection anyway.

It’s also worth noting that anemones do poorly in captive conditions and have a short lifespan.

Some species do better than others, though, so you might manage to accommodate them in a personalized setup.

Just keep in mind that anemones will only have an aesthetic role, given that clownfish bred in captivity don’t really need them.

Can You Keep Anemones in Aquarium?

Yes, you can, provided you understand the animal’s needs.

In essence, you need to consider several aspects when looking to create an anemone tank:

  • The species itself – Not all species of anemones require the same parameters. Depending on the species, you may need to ensure different temperatures, lighting conditions, feeding options, water flow, overall layout, etc.
  • Matured tanks only – You should never add your anemones to an immature tank. Complete the cycle first so your anemones can adapt to the environment more easily. Ammonia and nitrites are poison to anemones, as they are for most aquatic animals inhabiting the ecosystem.
  • Optimal feeding – Anemones will usually get their nutrients from the water column and their symbiotic relationships with algae. So, they don’t need feeding as often as your fish, but they still need a boost of nutrients occasionally. The feeding frequency also varies based on the anemone species. Some are fine with a couple of feedings per month, while others may require weekly meals to remain healthy.

Generally speaking, anemones are not difficult to maintain, but they are pretentious in terms of water conditions.

Parameter stability and clean waters are vital for your anemones to keep them healthy and growing.

What do Anemones Eat?

Anemones are carnivorous predators, so they prefer protein-rich live foods. These include small fish, shrimp, small crustaceans, scallops, clams, etc.

Different anemone species have different feeding patterns, with some eating more and more often than others.

Make sure you adapt to your anemone’s preferences to keep it healthy and satisfied.

These are sensitive organisms that require specific living conditions, a nutritious and balanced diet being one of them.

Will a Clownfish Eat an Anemone?

Not, but yes. This is a somewhat confusing topic, so allow me to un-confuse it.

Clownfish don’t eat anemone, as they recognize them as beneficial symbionts. Instead, they eat some of their dead tentacles if such an occasion should arise.

Clownfish also display a feeding behavior around anemones that may cause the wrong impression that they’re eating or attempting to eat anemone tentacles.

In short, they will suck in and spit an anemone tentacle occasionally, as if they’re trying to have a taste. This isn’t because they’re trying to eat it, but rather to eat what’s on it.

Anemone tentacles can grow algae, parasites, and other microorganisms which the fish can collect quite easily.

Will Anemone Eat a Clownfish?

Most anemones don’t eat clownfish, but some will. The first that pops to mind is the condy anemone.

This is a large and dangerous animal growing up to 6 inches tall, 12 inches wide, and with a radius of at least 16 inches.

It has long and powerful tentacles, and, most importantly, it doesn’t share the same environment with the clownfish.

Since the condy anemone and clownfish have never interacted with each other, the anemone will consider the fish prey. The problem is that the clownfish won’t distinguish between different types of anemones, so it will most likely try to host it.

This can only lead to carnage, as the anemone won’t hesitate to attack and consume your clownfish if given the chance.

So, always be mindful of the type of anemone you’re adding to your clownfish tank.

Do All Types of Clownfish Live in Anemone?

In the wild, yes, all fish host some type of anemone if they happen to find one. The situation is vastly different in captivity, where clownfish no longer require the assistance of an anemone.

So, you don’t need to get one for your clownfish, but you can if you want more diversity in the tank.

Just make sure you stick by 2 things:

  • You care for the anemone properly
  • You choose the right species so that the anemone won’t consume the clownfish

If you’re not that experienced in anemone keeping, I recommend skipping them altogether.

These animals are more pretentious than your typical aquarium creature, and you may have difficulties accommodating them as a novice aquarist.

Conclusion

Anemones and clownfish are notorious sweethearts in the wild, but not so much in aquariums.

They don’t need one another in captivity, but they can sure cohabitate peacefully, provided you ensure optimal conditions for them to thrive.

I recommend always weighing the pros and cons to determine whether anemones are worth the trouble. I say this because, in most cases, they don’t. 

avatar 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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