Clown Fish Anemone Relationship

There is no sure evidence about the clownfish immunity from anemone’s stings but, the most realistic and commonly accepted theory says that clownfish have secretory cells.

They produce a thick mucus coating all over their body, and this is able to protect from the deadly stingy tentacles.

The little poisonous darts that are within the tentacles of the anemone are called nematocysts.

Normally, when fish comes in contact with anemone’s tentacles, then the nematocysts or stinging cells discharge, paralyzing the victim.

Clownfish evolved a mucus chemistry which does not stimulate the nematocyst's discharge, so that tentacles are not tempted to kill the clownfish.

The mucus coating may be based on sugar rather than proteins so anemones are unable to recognize the fish as food and do not attack the clownfish.

This seems to be the reason why clownfish can safely swim among the anemone’s tentacles without being killed.

The above theory should be confirmed by the fact that that it takes many days for a clownfish to adapt to a new species of anemone.

Clownfish are the only species that are not stung by anemone’s tentacles and, on the contrary, receive protection by them.

In the aquarium life, to lack of predators, the presence of the anemone

(and its protecting tentacles) is not strictly necessary and clownfish can be well kept even without anemones in the tank.

Clownfish have bright colors which attract larger fish to the anemone.

Also, the movement of the clownfish attracts other fish to the anemone, which becomes a dangerous hunter and targets preys with the stingy tentacles.

If they approach too close, the larger fish are stung by the anemone’s tentacles and eaten as prey.

At this point, predators of the clownfish become victims of the anemone.

They feed each other respectively.

The clownfish eats undigested matter left by the host sea anemone.

They snack on  leftovers from prey fish of the anemone.

Clownfish also eat dead tentacles and this helps to keep the sea anemone healthy.

Last but not least, the clownfish also eats the algae swept into the anemone tentacles.

The  sea anemone eats what the clownfish excretes, as they represent nutrients that the anemone needs.

In return, the clownfish rids the anemone of parasites and debris, protects it from invaders and defends the anemone from attacks of natural predators such as the butterfly fish.

Once an anemone has been adopted, the clownfish marks out its territory (around 30cm) and will defend it firmly, as this fish is semi-aggressive and they are not scared to fight against similar or even bigger sized fishes.

They may be also aggressive towards other clownfish belonging to a different species.

In the wild, if the clownfish is removed, then large butterfly fishes will eat the anemone.

This predator has a long trumpet-like mouth, which is able of biting off whole anemone tentacles.

Another advantage for the sea anemone is given by fact that clownfish provides enhanced water circulation through the anemone by means of fluttering of its fins while swimming around.

Anemone  selection

In the wild, small groups of clownfish inhabit in a single anemone.

Clownfish are selective when they need to choose its host anemone.

They are generally highly host specific and each species of clownfish has its own preference when choosing a anemone as life “partner”.

When kept into a aquarium, above is the reason why it is really important to avoid putting the fish with the wrong anemone.

As far as scientists know, there are only 10 out of more than 1,000 types of anemone that have the ability to host clownfish. 

You may be also interested to read the clown fish anemone compatibility page.

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