The Wels catfish went to schools and reached more than 5,500 Portuguese pupils

The LIFE‑PREDATOR project — PREvent, Detect and combAT the spread Of SiluRus glanis in south European lakes to protect biodiversity — co‑funded by the European Union through the LIFE programme and developed in partnership between Portugal, Italy and the Czech Republic, was created to halt the advance of the Wels catfish or European catfish, the largest freshwater fish species on the continent, capable of reaching 2.8 metres and 120 kilos.

Native to the major rivers of Central Europe, it was introduced in Spain in the 1970s, reaching Portugal between 2006 and 2008 through both natural and assisted dispersal along the River Tagus. Today it is considered one of the invasive species with the greatest impact on native populations in the Tagus basin.

Nationally coordinated by Filipe Ribeiro, professor at the Faculty of Sciences of the University of Lisbon and researcher at MARE | ARNET, the Portuguese team of the project defined from the outset that stopping the Wels catfish also meant going into schools — and that is how the educational programme was born, bringing the fish from Portugal’s rivers to thousands of children.

One day in Arruda dos Vinhos

At Externato João Alberto Faria, in Arruda dos Vinhos, more than three hundred 2nd- cycle lower‑secondary pupils spent a morning discovering a world that, until then, was practically unknown to them: that of the freshwater fish living in the country’s rivers and streams. The visit, led by the Fish Invasions Lab team from MARE, was one of around sixty that have brought LIFE‑PREDATOR to Portuguese schools.

Upon arrival, pupils and teachers were already waiting for the researchers from the faculty who had come to talk about fish. The activities began in the gym, where the children looked for the best places to sit. They were treated to an interactive presentation about the fish of Portugal’s rivers: native species, invasive species, migratory species, and the Wels catfish. Where it lives, how big it grows, what it eats, the impacts it has on native fish, and the solutions available to halt its spread were some of the topics covered.

Next, two groups were formed. One stayed in the gym with card games — “As Invasoras à Espreita” — and puzzles, and also had the opportunity to observe Wels catfish vertebrae, understand how their size varies with the length of the fish, and how the animal’s age can be calculated from them.

The other group headed to the Rio Grande da Pipa, which runs through Arruda dos Vinhos, where a team of researchers was waiting to talk to them about scientific sampling methods. There they carried out a demonstration of electric fishing, which allowed them to collect several species that were later placed in an aquarium for live observation: an eel, a Portuguese nase, a verdemã, a barbel, a frog, and even an invasive specimen of the red swamp crayfish.

At the end, when asked what they thought, the pupils did not hide their enthusiasm. “It was really cool because we learned lots of things about fish,” one of them summed up. Another said he had never touched a fish before and enjoyed it. One of the parts that surprised them most was the journey of eels — “they travel a very, very long way,” explained a pupil, referring to the migration of these animals between the sea and the rivers. Some admitted they had changed their minds about fishing: “I thought fishing was always bad, but we actually have to fish to protect,” realised one girl, after learning that sustainable scientific fishing is part of the researchers’ work. And when asked what they would tell their parents at the end of the day, the answers came thick and fast: that there are 71 freshwater fish species in Portugal and thirty thousand worldwide; that fish make huge journeys to reproduce; and that the Wels catfish is “not good at all for human life” because “it eats the fish” and “reduces things we can also eat.”

How do you build a session that keeps attention?

The sessions always follow a similar structure, adjusted to the age of each class. “We have the first part, which is a presentation — very interactive — and then we have an activity section that is adapted differently. In 8th grade we end with a Kahoot!. With the younger ones we play the memory game, which everyone knows. ‘As
Invasoras à Espreita’ is more for the 3rd, 4th and 5th grade, who already read more fluently,” explains Mafalda Moncada, researcher in the group and responsible for the educational programme.

Behind this age‑based division lies a process of constant reinvention. Mafalda Moncada explains that she began with presentations already used by the team, but felt it was necessary to go further. “The part of the games are more challenging. The memory game never fails. The puzzles never fail either. And then I thought it would be nice to have a branded game. I had to battle with it a bit,” she recalls, referring to the creation of ‘As Invasoras à Espreita’, an adaptation of the classic cops‑and‑robbers’ game to the world of rivers, in which native species try to find their pair while invasive species attempt to eliminate them, and a biologist chases the invasive species to stop them. “So far it has been a success,” she sums up.

The initial presentation also has its own memory tricks. Each pupil is given a cardboard card featuring a freshwater fish species from Portugal’s rivers, indicating whether it is native, invasive or migratory, its level of endemism, or its extinction risk. “You are the ruivaco. Here is the Portuguese flag. Why? Because in the whole world it only exists in Portugal,” explains Filipe Ribeiro, describing how pupils visually group themselves by category throughout the session. “It’s a lot of information, but one thing they never forget is the fish they have in their hands,” says Mafalda.

A goal pursued school by school

This visit was one among many, and its reach can only be understood in context. According to Filipe Ribeiro, the LIFE‑PREDATOR proposal set an ambitious target, but one that seemed perfectly achievable over the project’s five‑year duration: five thousand children and fifty schools, with priority given to the municipalities along the Tagus River. “Within the entire project area, we established territorial priorities. The Tagus riverside municipalities are where known populations of Wels catfish exist, and those were the main municipalities we wanted to act in,” he explains.

The programme began in January 2025, when Mafalda Moncada started working full‑time on this component of the project. A year and a half later, the numbers had already surpassed the initial goal: 59 schools visited and almost five thousand six hundred pupils reached by June 2026.

Such growth requires behind‑the‑scenes work that few people see. “We have the advantage of having someone dedicated full‑time. Calling schools, insisting, making bookings. It’s all very labour‑intensive,” admits Filipe Ribeiro, describing Mafalda Moncada’s efforts to schedule activities with city halls and school clusters that are not always available.

In the field, she is almost always accompanied by Diogo Ribeiro. “During the activities Mafalda is always supported by one of us. Almost invariably it ends up being Diogo,” says Filipe.

It was in Gavião that one of the project’s most impactful moments took place. A visit to a school coincided with that of the coordinator, along with the rest of the Czech and Italian partner teams of LIFE‑PREDATOR. “We were there the whole day. It was quite a big event. When the colleagues arrived, we were just starting a Kahoot!. The entire LIFE team ended up doing it as well,” recalls Filipe Ribeiro. “Even though everything was in Portuguese, the Czechs and Italians took part and were impressed. Arriving and seeing an event with
more than three hundred pupils is something remarkable.”

The lack of knowledge that surprises — and the bridges that are built

It was not only the numbers that surprised the team; it was the extent of the unfamiliarity they encountered along the way that struck them most. Mafalda recalls asking pupils at one school which freshwater fish species they knew, and one of them confidently replied: “fish fingers”.

Filipe Ribeiro has a similar story, from a training session with the GNR in which he showed an image of the codfish — and no one in the room recognised it, as they were all used only to the triangular shape of the salted fish already prepared for sale.

But it is the generational connection that surprises Filipe the most: “Sometimes I feel we are bringing memories of the past to the new generation,” he says, recalling the fish that today’s pupils’ grandparents used to catch when they walked barefoot along the stream — bordalos, barbos, bogas — at a time when people still went into the water without fear of broken glass or pollution. This bridge between generations is also, for the team, proof that
the message goes beyond the classroom, with cases of children who took the conversation home and relatives who, weeks later, confirmed to the team that the topic had come up at dinner.

Asked about the programme’s goals, Mafalda Moncada has no doubts. “I think we had three main objectives: to introduce freshwater fish, the issue of invasive species, and the Wels catfish, because it is the target of our project.” And as for what truly remains once the team leaves the school, she sums it up: “What I think stays is, at the very least, that freshwater fish exist, and that some have always been here and others have not. There is a lot of diversity. These two messages alone are very important.”

There is also a call to action that the team repeats in every session: to take the conversation home. When confronted with the question of what to do about the Wels catfish — and the tonnes of fish that would need to be removed from the rivers — pupils’ answers are usually, according to Mafalda, as natural as the one heard in Arruda dos Vinhos: “catch it and eat it”.

As for the future, after the end of the European funding that supports LIFE‑PREDATOR, Filipe Ribeiro has no doubt that it is worth continuing to look for ways to carry the project forward. “There is a great level of personal satisfaction on our part. The result is immediate. The impact is real. I think it creates a good dynamic within the team.”