Potentially lethal lionfish are being seen on a weekly basis according to aquarists concerned they pose a threat to both humans and fish shoals.

The latest one was seen off the Lartington wreck about five miles southwest of Bermuda by amateur diver Rebecca Zuill, on Monday.

She said: “We got within a foot of it. It didn't seem to be shy.”

The foot-wide fish, normally native to the Pacific, packs a poison which can kill the elderly, children or ill people. There is no antidote.

However most people will survive the stings, which can be treated by hot water.

Aquarist Patrick Talbot said a volunteer at the Bermuda Aquarium and Zoo was compiling data to see how bad the problem was.

He said: “We seem to be getting reports every week.”

He urged people to report sightings - preferably using GPS coordinates - and said collectors had retrieved several fish after getting calls from the public. The fish like to stay in one region said Mr. Talbot.

Lionfish can come close inshore, with one found in a rock pool in Devonshire Bay a few years ago.

Mr. Talbot said lobster divers looking under rocks were most likely to be in danger from the fish's poisonous spines.

The spines are so hazardous that some jurisdictions insist two people must be present when they are dissected until the spines have been safely contained.

The fear is they will go after local fish. Mr. Talbot said: “We don't know how they are going to impact the environment.”

Aquarium Curator Dr. Ian Walker said no hard evidence had come to light on why the fish are now in Bermuda waters. He said one theory was they had been released by hobbyists while another theory said they got into the Atlantic after fish shops were destroyed in Hurricane Andrew.

He said they posed a danger to juvenile local fish.

“They are generally a voracious predator.”