"We want to protect our inland water bodies from invasive species," Ramalingam Chandrasekar said, adding it was aimed at protecting the livelihoods of fishermen on the island nation.

The import, sale and transportation of Redline Snakehead, Knife Fish, Alligator Gar and Piranha, imported from Southeast Asia, will be banned from Saturday, the minister said in a statement.

Snakeheads, which can grow to over three feet (one metre), were rapidly multiplying in a lake in the northwestern part of the island, threatening the native species.

Officials believe they may have been released into the Deduru Oya lake by owners who could no longer care for them.

The fisheries ministry has organised a competition for anglers to catch Snakeheads, coinciding with the ban on Saturday.

Sri Lankans are not used to consuming Snakehead fish which is a voracious predator, eating smaller native fish and amphibians and disrupting the ecological balance.

Pet owners rearing the four species have been asked to notify the authorities and hand them over so the fish can be confined to state-run aquariums.