Arapaima gigas invading the Amazon region in Bolivia, being a herbivorous fish weighing up to 200 kg, becomes a threat to native wildlife but is a valuable product for fishermen.
No one knows exactly when Arapaima Gigas first arrived in Bolivia. Many experts believe they escaped from fish farms in Peru, where they are native species. From there, they spread into the rivers of Bolivia.
Arapaima gigas, one of the largest freshwater fish in the world, can reach up to 4 meters in length and weigh over 200 kg. According to estimates, Arapaima gigas invades an additional 40 km each year into the rivers of the Amazon region. Its size and herbivorous nature pose a serious threat to native fish species, according to Federico Moreno, director of the Center for Aquatic Resources Research at the Autonomous University of Beni.
‘They are territorial fish. They occupy a water area and drive away native species. It’s one of the serious problems. Other species flee from predators and move to other water areas, much farther and more difficult to access,’ Moreno said.
Arapaima gigas is a voracious eater, growing at a rate of 10 kg per year in its early years, according to biologist Fernando Carvajal, an expert on this fish species. “In the first few years of life, they grow at a rate of 10 kg per year. That means they eat a lot of fish,” he said.
Unlike other predatory fish like piranhas, Arapaima gigas has small, non-sharp teeth. However, this doesn’t stop them from consuming piranhas and various other fish species, along with plants, soft-bodied animals, and birds. Arapaima gigas feeds on a variety of items like a giant vacuum cleaner, and it instills fear in any carnivorous fish attempting to eat its offspring.
Carvajal mentioned that there is no definite data on the impact of Arapaima gigas, but according to local fishermen, the population of some native species is gradually decreasing. “In one or two decades, Arapaima gigas will spread to all potential areas where this species can live. We know that globally, most invasion cases are harmful to nature. Invasive species are considered the second major cause of biodiversity loss, after habitat destruction,” he warned.
However, for local fishermen, the appearance of Arapaima gigas also brings significant benefits. Fisherman Guillermo Otta Parum said that initially, he was worried but soon realized their potential. “When I bring the first fish home, I will give customers small pieces to try and savor the flavor,” Parum said. Currently, they have become a dish throughout Bolivia.
The challenge for fishermen is to search for Arapaima gigas in the vast Amazon region. This species has lung-like organs and regularly surfaces to breathe air, preferring calm water areas. They like to live in ponds and marshes but will migrate when they sense danger.
Scientists like Moreno hope that capturing them will help control the population of Arapaima gigas. ‘Keep hunting them, keep capturing them. That can maintain the balance between different species,’ he said.
