Alien 'ghost' fish are taking over...

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Lionfish are invisible to the smaller fish they view as prey - and this is very bad news for the Caribbean.

A new study by James Cook University scientists Oona Lönnstedt and Professor Mark McCormick suggests this is one reason for the alien invader's incredible success in the Caribbean, where these invasive predators are eating their way through the reef ecosystem.

Graduate student Ms Lönnstedt and Professor McCormick have found that lionfish are virtually undetectable by prey, acting as ghosts and able to feed on anything and everything without being discovered until it’s too late.

"We tested the response of small prey fish to three different predators, one of them the lionfish," Ms Lönnstedt said.

"Surprisingly, the common prey fish were unable to learn that the lionfish represented a threat, which was very different to their response to two other fish predators.

"Lionfish were able to sneak up on their prey and capture every single one, while the other predators had much lower feeding success."

This ability to bypass a very well-studied learning mechanism commonly used by prey to learn new risks is a world first, and has in part led to the astounding success of lionfish in the Caribbean.

With release from any natural enemies in their new system and no problem catching food, the lionfish are practically unstoppable.

The paper 'Ultimate Predators: lionfish have evolved to circumvent prey risk assessment abilities' is published in the latest issue of PLOS ONE.

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