On the Tetra's TrailLevels 3 and 4

Study the mystery of evolution in verdant Mexican valleys! Further Details

On the Tetra's TrailLevels 3 and 4

Study the mystery of evolution in verdant Mexican valleys! Further Details

Get involved with incredible scientific projects!
Science camps which could change the world!
Exceptional adventures and real projects for sustainable development


Take a trip to the heart of the Mexican mountains to discover mysterious small, cave-dwelling fish, and take part in a research program Research Program Collaborate with scientific organizations. Actively take part in participative science research programs. All this is possible with our plankton discovery sailing expedition. by collecting scientific data from the rivers or caves in which these unusual fish hide. Swimming and spelunking will be abundant.

The stay

Have you heard of the Astyanax mexicanus (Mexican Tetra)? These little fish generally live in the rivers of Mexico and the south of Texas. But not always! Some time ago, a part of the population tumbled down into the caves and evolved independently in the darkness of their surroundings. Thus, while these fish are very common on the surface of the water, there are only twenty-nine cave-dwelling populations of these fish known to us.
Furthermore, these cavernous fish are morphologically completely different and behave differently: they no longer have eyes, they have become depigmented, have a large mouth and a different body, etc.

The existence of a common ancestor for the two subspecies allows us to compare the surface and cavernous populations, and therefore to study the evolution and adaptation of an extremophilic subspecies to its new environment, that is to say, living in conditions that are deadly for the majority of living organisms.
These cavernous fish are thus extraordinary models for many areas of biology, including medicine, genetics, developmental biology, neuroscience, behavioral science Science La science est désormais l’affaire de tous. Découvrez la science d’une manière ludique et active. Nous vous proposons d’en découvrir plus sur nos expéditions à la voile, découverte du plancton. , population biology and many more!

The research project

The objective of this program is to study the ecology and behavior of the cavernous Astyanax mexicanus in their natural habitat.

Complying with the line of study of this scientific program, here is a list of the research activities on which you will be potentially working, depending on requirements:
-  Knowledge of the fish’s environment and seasonal changes
-  Nutritional habits of the fish (quality, quantity)
-  Olfactory ability of the fish
-  Reproduction (gonadosomatic ration, maturation of gametes, size, weight)
-  Morphological variation in the various populations
-  Genetics of the populations and phylogeography (DNA sample analysis)
-  Demography (capture-recapture method)
-  Behavior in situ (video recording with possible use of drones)

This will be translated in the field by data-type manipulations on water, fauna and flora, physico-chemical analyses, DNA surveys (non-invasive method), specific experiments in natural pools or swimming pools placed directly on the ground, and the use of drones for recognition, video recordings and cartography. The protocols used are those provided by the CNRS laboratories with whom the Tetra program collaborates.

All our studies will be non-invasive. It is one of the basic principles of the program.
The data collected in the field will be usable by the entire Astyanax mexicanus research community, and we’ll be collaborating very closely with “Evolution Génomes Comportement Ecologie” and the Institut des Neurosciences Paris-Saclay laboratories located in Gif-sur-Yvette, not far from Paris. The analysis of the data you collected will be done in collaboration with them.

Finally, your participation in this program will allow researchers to monitor the collected data in the long term. Through this expedition based on the principle of citizen science, you will be able to offer the research community a volume of data that they are unable to harvest themselves.

Concepts Learned during the Camp

Population Biology - Biodiversity - Ichthyology - Evolution - Adaptation - Genetics - Conservation - Ethology - Ecosystems - Sampling - Non-Invasive Sampling - Counting - Computing - Problem-solving

Equipment Used

Hand nets - Nets - Sensors - Drones - Acoustic and Video Equipment - Portable Pools and Aquariums - Masks - Helmets - Infrared Cameras - Infrared Lamps - Raspberry Pi - Computers - Precision Balances - Portable Spectrometers

The location

In the center of the luscious, dry, tropical vegetation of the mountains in the Mexican state of San Luis Potosi are the caverns and rivers in which these mysterious little fish live.
Beautiful landscapes, rich and surprising biodiversity, unforgettable encounters: that’s what awaits you in this remote and mysterious region!

Far from tourist infrastructure, you will plunge into the heart of a country with rich and fascinating cultures and traditions.

With the dry season extending from October to April, you will find yourselves a far cry from the European winter you’re used to. A dry and sunny climate awaits, without being too hot. An ideal time for surveying the hills, villages, rivers and caves!

Ten stations for field experiments were chosen by the researchers of the CNRS: five for surface fish, five for the cavernous. A station is an area with a homogeneous environment and where evolutionary history is sufficiently clear and distinctive to justify its selection. Of these, the stations chosen for the expeditions are those not at risk.

Day to day proceedings

Out in the field, the days will be dedicated to work in the caves or rivers depending on the scientific needs and the weather. You will go to the site in question in the morning where you will spend the day carrying out science experiments and practical work in a pleasant atmosphere.

The caves we will be visiting are rather spacious, save one or two narrower passages. They can be reached without any previous experience in spelunking. For safety reasons, you will be roped together in certain steeper passages. A spelunker will be monitoring you during all trips to the caves.

Between each field site, discovery days will take place to enjoy the aquatic wonders (waterfalls, rivers, natural pools), panoramas and the wealth of Mexican culture.

ATTENTION: In order to participate in this expedition, it is important that you are in good physical health, know how to swim, and do not suffer from claustrophobia, nyctophobia, ichthyophobia, aquaphobia or from another affliction related to water and caves.
No additional training in speleology (spelunking) is necessary. Safety during these activities will be ensured by a qualified instructor.
Moreover, certain caves are inhabited by fungi, which can cause histoplamosis if you do not wear any respiratory protection. For this reason, protective masks will be provided to protect yourself from the mushrooms and explore the caves safely.

The team

Julie Rode is co-supervisor of the Astyanax(ion) Research Program. A committed “pantherist,” the study of this big feline made her discover — in addition to an infinite number of other things! — the wonders of population genetics. Trained in physics, she is currently undergoing a career change.

Stéphane Rode is co-supervisor of the Astyanax(tion) Research Program. Also a committed “pantherist,” he loves adventure, nature and research. He has a number of expeditions around the world to his name and organizes them to enable him in sharing his passions with the world.

Solène Touzeau has overseen the PERCEPTION research program for six years. A biologist by trade, she coordinates the science projects of the Up Amongst the Trees and All Along the River camps in Provence, as well as All through the Amazon in French Guyana. She’s now dedicating herself to the “ON THE TETRA’S TRAIL” project as the science and logistics coordinator.

During your stay, you will also have the opportunity to meet one of the members of the CNRS teams of the EGCE and Neuro-PSI laboratories located in Gif-sur-Yvette who is studying the Astyanax mexicanus.


Accommodations will be in one or more hotels or guest houses near the caves in the vicinity of Ciudad Valles, usually in double or triple rooms.


Day to Day Schedule

Here is the typical breakdown of a stay. It will, however, be adjusted according to the period, weather and scientific needs.

Day 0: For participants flying from Paris, the meeting will take place in the morning at the Muséum national d’histoire naturelle to become familiar with the protocols that will be used on-site. The whole team will then go together to the airport to catch the plane in the evening.
For those who are unable to meet at the museum, the protocols will be sent out so that you can get acquainted with them before leaving for this fabulous adventure!
Day 1: Arrival in Mexico City, travel to the first city stop-off, settling in and adaptation to Mexican culture
Days 2 and 3: Field work in the first cave or river
Day 4: Discovery day of the region and/or rest
Days 5 and 6: Field work in the second cave or river
Day 7: Day of discovery of the region and/or rest
Days 8 and 9: Field work in the third cave or river
Day 10: Day of discovery of the region and/or rest
Days 11 and 12: Field work in the fourth cave or river
Day 13: Day of discovery of the region and/or rest
Day 14: Back to Mexico City for the return flight

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