"It's a 'Finding Nemo' story," marine biologist Brice Semmens, of the University of Washington, Seattle, told New Scientist magazine.

In the blockbuster animated film Nemo, a clownfish, strays from his home and ends up in a fish tank in a dentist's office in Sydney, Australia while his over-protective, timid father searches the oceans for him.

"Individuals are releasing their pet fish with the best of intentions, but in the wrong ocean. It is a really bad idea," Semmens added.

Exotic fish from the Pacific and Indian oceans and the Red Sea, including the predatory lionfish, varieties of angel fish and tang have been sighted off the coast of Florida.

If the fish breed and establish populations they could endanger local species.

The lionfish, which has now been spotted in waters from Florida to New York, is particularly worrying because it preys on a variety of fish, shrimps and crabs, according to the magazine.

"In the coming weeks the US National Oceanic & Atmospheric Administration and representatives from the aquarium industry will join forces to educate the public about the dangers of dumping pet fish into the ocean," the magazine said.