An Alligator Gar fish, caught in a lake in Kolkata, has set alarm bells ringing, with experts saying the predatory creature can kill all other fishes around and also attacks humans, reported the Hindustan Times. The fish, which is generally found in North and Central America, grows up to eight feet.

“This is the first time that this species has been caught in the city. We would like to send a team and collect the specimen. We will also try to explore the lake to check if their population has proliferated and how big is the threat,” said KC Gopi, a fish expert with the Zoological Survey of India.

Andhra Pradesh and Telangana are already struggling to curb of menace of this species, one of whose kind was found in a well in Dadar, Mumbai, in 2015. “It is a highly carnivorous fish. It not only kills other fishes but there are reports of it attacking humans too. The fish’s egg is also poisonous. It has no natural enemies and hence can become invasive in no time destroying the local ecosystem and biodiversity,” said Mathe Rajeev Mathew, member of the National Biodiversity Authority and the Telangana State Biodiversity Board.

The angler who caught the fish from Subhas Sarovar lake in Kolkata's Belaghata neighbourhood two months ago said the 3.5-ft-long fish tried to attack him and also killed another fish he had caught before. The fish that weighed more than 5 kilos was later killed and eaten by some locals who said that its skin was so tough that they had to use an axe to chop it up. According to experts, the fish is generally smuggled from abroad for aquarium keepers who often abandon them when they start growing.

“We have had a similar experience with another aquarium fish called the Crocodile fish while working in East Kolkata Wetlands. They are bought by aquarium keepers and then released into wild when they grow big. Crocodile fish are now found in almost every pond and lake in Kolkata and are destroying the local biodiversity,” said NGO South Asian Forum for Environment chief Dipayan Dey.