‘Monster’ fish can grow to monstrous sizes: Experts

They say people should do research before buying one, illegally releasing them is irresponsible

An avid fish collector for the past 11 years, Mr Clarence Ng, 25, has reared many species of "monster" fish, such as gars, snakeheads and bichirs.

Hooked on angling in his teenage years, Mr Ng's first encounter with a giant snakehead in 2010 sparked his fascination with such "monster" varieties.

"The giant snakeheads follow their children around and are very territorial.

"They attack anything that goes near them, even your hooks," said the digital designer.

Mr Ng bought a baby snakehead after spotting one in an aquarium shop when he was about 14 and has started rearing such fishes since, including the smaller variant alligator gars.

On Feb 14, a "monstrous" alligator gar carcass was seen at MacRitchie Reservoir, raising concerns of the illegal release of fishes into water bodies.

The species, which can grow up to 2.5m long, is native to North America and does not belong here.

Mr Ng said that owners who illegally release fish are irresponsible and should think about the environmental consequences.

"When they are unable to care for it, they just release it," he said.

He suggested that such owners should visit Love Fish Singapore on Facebook, a community dedicated to rehoming fish.

While an 8cm baby alligator gar can be bought for around $5 at aquarium shops here, Mr Ian Toh, owner of Toh Aquarium, often advises potential buyers to reconsider, because of its rapid growth.

"They eat small fish, so some people find it fun to have them as pets, but when they grow bigger, they become quite a problem," Mr Toh said.

"Some (customers) have even asked me if I can take them back, but I tell them I don't have the space for it."

Mr Lionel Lau, 32, an aquarium hobbyist, said that some alligator gar collectors are ignorant of the "sheer size" the species can reach because they did not research before buying.

"Potential owners should consider beforehand if they have the space to rear these monster fishes before getting one," the digital marketer added.

Dr Tan Heok Hui, an ichthyologist - or a marine biologist who studies fish - from the Lee Kong Chian Natural History Museum, suggested that ownership of such exotic fish be licensed.

He noted that the arowana, a prized ornamental fish, is microchipped, similar to cats and dogs.

Though the illegal release of gars may pose a threat to other species in the ecosystem, nature has a way of curbing them.

Dr Tan said a temperate species like the gar requires a cool season to be sexually reproductive, adding: "In a tropical country like Singapore, they may not be able to breed naturally."

Mr Lim Liang Jim, group director of the National Parks Board's (NParks) National Biodiversity Centre, said that NParks staff regularly remove invasive species in Singapore's nature reserves and other green spaces when they spot them.

Offenders caught releasing animals in parks and nature reserves face fines of up to $50,000, while those who release wildlife can be fined a maximum of $5,000.

This article first appeared in The Straits Times.