The wels catfish went to schools and reached over 5,500 Portuguese students
The project LIFE-PREDATOR - 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 curb the advance of the wels catfish, or European catfish, the continent’s largest freshwater fish species, capable of reaching 2.8 meters and 120 kilograms. 
Native to the large rivers of Central Europe, it was introduced in Spain in the 1970s, reaching Portugal between 2006 and 2008 through natural and assisted dispersal along the Tagus River. It is now 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 project’s Portuguese team decided, from the very start, that curbing the wels catfish also meant going into schools, and that is how the educational program was born, one that has already brought the river fish of Portugal to thousands of children.
A day in Arruda dos Vinhos
At Externato João Alberto Faria, in Arruda dos Vinhos, more than three hundred primary school pupils spent a morning discovering a world that, until then, had been 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 visits that have taken LIFE-PREDATOR into Portuguese schools.
On arrival, pupils and teachers were already waiting for the faculty researchers who had come to talk about fish. The activities began in the gymnasium, where the children jostled for the best seats. 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 curb its advance were among the topics covered.
Two groups were then formed. One stayed in the gymnasium with card games, ‘Invaders on the Prowl,’ and puzzles, and had the chance to examine catfish vertebrae, see how their size varies with the fish’s length, and learn how they are used to work out the animal’s age.
The other group went to the Rio Grande da Pipa, which runs through Arruda dos Vinhos, where a team of researchers was waiting to tell them about scientific sampling methods. There, they held an electrofishing demonstration, which allowed them to collect several species, later placed in an aquarium for live observation: an eel, a boga-portuguesa, a verdemã, a barbel, a frog, and even an invasive specimen of red swamp crayfish.
In 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,” summed up one of them. Another said he had never touched a fish before and enjoyed it. One of the things that surprised them most was the journey eels make: “It goes a really, really long way,” explained one pupil, about the migration of these animals between the sea and the rivers. Students admitted they had changed their minds about fishing: “I thought fishing was always bad, but actually we have to fish to protect,” realized one pupil, 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 pouring out: 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, well, “it is not good at all for human life,” because “it eats the fish” and “it reduces the things we can eat too.”
How to build a session that holds attention
The sessions always follow a similar structure, adjusted to each class’s age. “We have the first part, which is a presentation, and it is very interactive, and then we have an activity part that is adapted differently for each group. In year 8, we finish with a Kahoot! With the youngest ones, we play the memory game, which everyone knows. ‘Invaders on the Prowl’ is more for years 3, 4 and 5, who can already read more fluently,” explains Mafalda Moncada, researcher in the group and head of the educational program.
Behind this division by age lies a constant work of reinvention. Mafalda Moncada says she started from presentations the team already had but felt it was necessary to go further. “The games’ part is more challenging. The memory game never fails. The puzzles never fail either. And then I thought it would be nice to have a signature game. I struggled with that one for a while,” she recalls, about creating the game ‘Invaders on the Prowl,’ an adaptation of the classic game of cops and robbers to the world of rivers, in which native species look for their match while invasive species try to eliminate them and a biologist chases after the latter to stop them. “So far it has been a success,” she sums up.
The opening presentation also has its own memory tricks. Each pupil is given a cardboard card showing a species of fish from Portugal’s rivers, indicating whether it is native, invasive, migratory, its level of endemism, or its extinction risk. “You are the ruivaco. Here is the Portuguese flag. Why? Because in the entire world it only exists in Portugal,” explains Filipe Ribeiro, describing how pupils visually group themselves by category throughout the session. “It is a lot of information, but one thing they do not forget is the fish they have in their hand,” says Mafalda.
A target pursued school by school
This visit was one among many, and its scale only makes sense in context. According to Filipe Ribeiro, the LIFE-PREDATOR proposal set an ambitious goal, but one that seemed perfectly achievable over the project’s five years: five thousand children and fifty schools, with priority given to the municipalities along the Tagus. “We set territorial priorities within the project’s whole area of action. The municipalities along the Tagus are where known wels catfish populations are found, and those were the main municipalities we wanted to focus on,” he explains.
It all began in January 2025, when Mafalda Moncada started dedicating herself full-time to this part of the project. A year and a half later, the numbers had already surpassed the initial target, with fifty-nine schools visited and almost five thousand six hundred pupils reached by June 2026.
That growth requires behind-the-scenes work that few people see. “We have the advantage of having one person dedicated to it full time. Calling the schools, following up, scheduling visits. It is all very labor-intensive,” admits Filipe Ribeiro, describing Mafalda Moncada’s effort to schedule activities with municipal councils and school groups that are not always available.
In the field, she is always accompanied by Diogo Ribeiro, “Mafalda is always supported by one of us during the activities. It always falls to Diogo,” says Filipe.
One of the project’s most striking moments happened in Gavião. A school visit that coincided with a monitoring visit by the rest of the LIFE-PREDATOR team, including the Czech and Italian partners. “We were there the full day. It was a big event. When our colleagues arrived, we were just starting a Kahoot!. The whole LIFE team ended up joining in too,” recalls Filipe Ribeiro. “Even though everything was in Portuguese, the Czech and Italian partners took part and were impressed. Arriving and seeing an event with three hundred-odd pupils is really something.”
The surprising gaps in knowledge, and the bridges they build.
It was not just the numbers that surprised the team; it was the scale of the lack of knowledge they came across along the way that surprised them most. Mafalda recalls asking, at one school, what freshwater fish species the pupils knew, and one of them answered, with complete conviction: “goldfish” (a popular breaded fish snack for children).
Filipe Ribeiro has a similar story, from a training session with the GNR (Portugal’s National Republican Guard) where he showed a picture of a live cod and no one in the room recognized it, as everyone was only used to the triangular shape of the salted fish already prepared for sale.
But it is the generational connection that has surprised Filipe most: “Sometimes I feel we are bringing memories of the past back to the new generation,” he says, recalling the fish that today’s pupils grandparents used to catch when they walked barefoot in the stream, the bordalo, the barbel, the boga, at a time when people still went into the water without fear of broken glass or pollution. For the team, that bridge between generations is also proof that the message reaches beyond the classroom, with cases of children who took the conversation home and relatives who, weeks later, confirmed to the team that the subject had come up over dinner.
Asked about the program’s goals, Mafalda Moncada has no doubts. “I think we had three main goals: raising awareness of freshwater fish, the issue of invasive species and the wels catfish, since that is the target of our project.” And on what really stays with pupils after the team leaves the school, she sums up: “What stays is, at the very least, that freshwater fish exist and that some have always been here while others have not. There is a lot of diversity. These two messages alone are already particularly important.”
There is also a call to action that the team repeats in every session: taking the conversation home. When faced with the question of what to do about the wels catfish, and the tons of fish that would need to be taken out of the rivers, the pupils’ answer, according to Mafalda, is usually as natural as the one heard in Arruda dos Vinhos: “fish them and eat them.”
As for the future, once the European funding that sustains LIFE-PREDATOR ends, Filipe Ribeiro has no doubt it is worth continuing to look for ways to carry on with the project. “There is a real sense of personal satisfaction on our part. The result is immediate. The impact is real. It builds a good dynamic within the team.”
Text: Vera Sequeira
Photographs: Jéssica Jacinto and Vera Sequeira