Kathmandu– An unexpected discovery of foreign fish species has stirred the scientific community and local fishermen in Belbari and Dhanpalthan of Morang. The Amazonian fish, known scientifically as ‘Pterygoplichthys disjunctivus’, was first spotted in Nepal’s Belbari region four years ago. This species, native to the Amazon River in South America, has been increasingly prevalent in East and South Asian countries in recent years.
Local researchers Jashang Limbu, Deepak Rajwanshi, Asmit Subba, and Laxman Khanal initiated the investigation into this unfamiliar species. Their efforts, supported by Chinese researchers Jinquan Yang and Chenhong Li, confirmed the fish as a new species for Nepal. Detailed studies on the fish’s habitat, physical and genetic characteristics, and behavioral patterns were conducted. The findings were published in the recent issue of the science magazine ‘Bioinvasions Records’.
In the magazine, it was reported that 43 samples of this species were collected from the Lohandra River, classified as level Q2. The fish was also found in two locations along the Lohandra River and in another site on the Damakthir River. The collected specimens, weighing between 200 and 300 grams, displayed an attractive appearance.
Researcher Jashang Limbu offered two possible explanations for the presence of this fish in Nepal. “It may have either escaped from someone’s aquarium into the natural river system or traveled from India via the river,” he said.
Limbu highlighted the potential ecological threat posed by this invasive species. “Regardless of how they arrived, once in Nepal, these fish compete with native species for food, habitat, and breeding sites, risking the extinction of our indigenous fish,” he explained. The invasive nature of Pterygoplichthys disjunctivus has already caused ecological imbalances in various countries.
This fish species, initially shy and motionless, can become aggressive, attacking and consuming baby fish when given the chance. “It has firmly established itself in the Lohandra River in Morang,” Limbu noted.
The research team’s investigations, which began in 2019, revealed the species’ growing presence in the Lohandra River. There is now concern about its potential spread to other rivers and commercial fish ponds in Nepal. “If it infiltrates commercial ponds, it will cause significant damage,” Limbu warned. Despite being popular as an aquarium pet, this fish is unappealing for consumption due to its lack of flavor.
The researchers have called for immediate action to control this invasive species. “More research and control measures should be implemented at the policy-making level,” they urged in their article. Failure to act could jeopardize the livelihood of fishermen, cause substantial economic losses, and disrupt the natural ecosystem.
Nepal is home to 260 fish species, including Pterygoplichthys disjunctivus. Among these, 18 species are foreign, while 17 are unique to Nepal.
The discovery of this Amazonian fish in Nepal underscores the urgency for increased awareness and proactive measures to protect the country’s aquatic biodiversity and ecological balance.
