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WRASSES, FISH WITH A THOUSAND RESOURCES

Why talk about them?

“We are capable of doing things that you humans can only imagine!”

Wrasses are a very large family with species that live in both tropical seas (about 500) and temperate seas such as the Mediterranean Sea. Many of them are famous for being cleaner fish.


Little Damsel Fish

“You know the damsels? The Napoleon fish? The thrushes? Here we are!


How we recognize them:

Given the great variability of shapes and colors, it is not very easy to distinguish them! Here are some curiosities that could help us:

  • First of all, they are called this way because of the presence of full lips, their distinctive feature;

  • They have very bright and brilliant colours, which change throughout their lives, but not only;

  • They often have a rounded caudal fin that allows for precise movements between crevices or corals;

  • Their size varies from a few centimetres to the 2 metres of the Napoleon fish!

  • They are very active fish during the day, while at night they remain hidden among the algae, crevices, or even under the sand.

Napoleon fish by profile swimming
Napoleon Fish, Sharm El Sheikh, Egypt


What do wrasses eat?

Their variability is also demonstrated in their diet: they eat fish, mollusks, algae, plankton, crustaceans, corals, invertebrates of all kinds. This not only makes them extremely adaptable but also ecologically essential for coral reefs and temperate regions in which they live.


The life of the wrasse

If in previous articles we were surprised by the sex of sharks or groupers, get ready because our wrasse friends have outdone themselves!

They can be both simultaneous hermaphrodites, that is, male and female at the same time, and protogynous (they are born female and at a certain point in their life become male), and protandrous (first male and then female).


Piccolo Pesce Donzella

“In this large family of 500 species, anything can really happen!”



Let's take the Napoleon fish as an example: it is born female, after reaching sexual maturity between 5 and 7 years, it becomes male. In the male, the particular protuberance begins to form above the head from which its name derives, as it resembles Napoleon's hat!


Cleaner fish are also protogynous: they are born females and create small harems with a dominant male. Once the male dies, the dominant female will transform into a male (between 2 and 4 days!) and take his place, while the largest of the others will become the dominant one. Thanks to the production of hormones, this delicate balance is maintained within the harem, not allowing immature females to mate until their turn comes!


Rabbit fish during cleaning service of two cleaner fish on black background
Rabbit fish during cleaning service of two cleaner fish

The coloration of wrasses

Coloration always says a lot in Nature, with a little attention it can tell us great secrets and amaze us every time!

In wrasses, coloration is influenced by sex, reproductive period, competition between males but also by environmental factors such as the type of seabed and seasonality.


Piccolo Pesce Donzella

“Well, not bad! Now it’s up to you to understand why we change color!



Juvenile wrasses are often quite dull in color, while adults are very brightly colored!

Our friend the cleaner wrasse goes from a black and white streaked with light blue to a beautiful bright blue that stands out against the surrounding coral reef!


Damsel fish swimming on the sandy bottom
Damsel, Sharm El Sheikh, Egypt.

The intelligence of the wrasse

That's why we want to tell you about them...

These cute animals were the first fish to be observed using tools to get food.

Wrasses are able to find bivalves like clams under the sand, moving it thanks to the snappy opening and closing movements of the gill covers, they manage to catch them, then they carry them to the rocks and drop them so that the shell breaks and they finally have their meal.

What does this mean?

The wrasse has a well-defined plan in its head to carry out its action, this plan is made up of many steps in succession.

This discovery has greatly changed the way of seeing fish, often considered not intelligent or not on par with terrestrial beings such as mammals and birds (the only ones so far capable of using tools), instead they too are able to think and be resourceful. If you are still not convinced, continue reading!


Piccolo Pesce Donzella

“What is intelligence to you? Wrasses versus primates”



  • Experiment:

Imagine being hungry: in front of us we have two plates with the same food but of different colors: one blue and the other red. If we start eating from the blue one, the red plate is taken away after 5 minutes and we can't eat it, if we start from the red one, the blue one remains and we can eat them both.


This experiment was proposed to a group of cleaner wrasses taken from the wild and to a group of primates including chimpanzees and orangutans. Obviously the trick of eating both plates had to be learned through experience and trial and error.

Who did better in your opinion?

Well, the wrasses took less time than our "cousins" to understand to start eating from the red plate in order to be able to have a complete meal!

Not content, those who had passed the test were proposed the reverse test and once again the wrasses prevailed! The curious thing is that the test was also done on younger specimens but the performances were clearly inferior to the adults, this shows that it is a mental ability that is not innate but that must be learned.


Where do we want to go with this story?


The sophisticated decisions of cleaner wrasses are dictated by their main daily activity: cleaning other organisms in cleaning stations!

Wrasses have figured out that some of their “customers” are “regulars” (blue plate) while others are just passing through (red plate); knowing these timings they also know who to offer their services to first. The passing customer, if not inspected quickly, could decide to leave at any moment and change cleaning stations, while the regular stays around for a long time.

In a normal “work” day, wrasses can clean even hundreds of customers and even reach 2000 interactions a day on the busiest days! This means that the only way to work well and earn a meal is to make strategic choices, that is, intelligent ones for the purpose you want to achieve!


Emperor Angelfish During Cleaner Fish Cleaning Service
Emperor Angelfish During Cleaner Fish Cleaning Service

P.S. This doesn't mean that primates are stupid, it simply means that they are better able to do other things based on their life needs, such as creating mental maps of the fruit trees in their forests with a ripening calendar to boot. (To the wrasse, this would honestly be of little use!!!)


Intelligence is therefore not to be measured by the size of the brain or by close relationship to humans; any living being can be very intelligent based on its survival needs, just like our friend the cleaner wrasse!


We talked about cleaning stations, cleaning stations and spas…But what exactly are they?

In the next article we will discover together the workplace of the cleaning wrasses!



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