An invasive snakehead fish species is threatening the livelihoods of fishers in northwestern Sri Lanka, aggressively consuming traditional fish and shellfish in the Deduru Oya reservoir. Over the past two years, fishermen have reported a sharp decline in usual catches, while snakehead fish, previously unknown in the country, have appeared in vast numbers.
Officials suggest the fish, common in Thailand and Indonesia, likely arrived as imported ornamental species released into the reservoir when they outgrew their tanks. Dr Kelum Wijenayake, an academic researching the species, notes that the snakehead has no natural predators in Sri Lanka's ecosystem, allowing its population to flourish unchecked. The fish can come to the surface to inhale oxygen and survive with minimal water.
With sharp teeth and strong jaws, snakeheads are aggressive eaters that damage the local ecosystem. They grow larger than native species; fisherman Nishantha Sujeewa Kumara once caught a 7kg specimen, while native species usually weigh under 1kg. Secretary of the local fishers association, Ranjith Kumara, said the fish cannot be caught using nets, only by angling, and that high-value prawns and other species have become rare since 2016.
Authorities organised an angler competition to control the population, but it was unsuccessful. Fishers now hope to turn the threat into an opportunity. Ranjith Kumara proposed promoting angler tourism as a consistent control method, providing alternative income for villagers engaged in fishing and farming.
Fisherman Sujeewa Kariyawasam produces salted dried fish from the invasive species, noting that while fresh snakehead has low market demand, the dried fish is a popular delicacy. “I am working to further develop this business. As demand grows, more snakeheads will be caught for production, helping control their population,” he said.
