Setting the catfish amongst the pigeons: The astonishing moment a fish leaps out of the water to catch a bird

Catfish in the Tarn River in south-west France are the only ones ever to be observed exhibiting the behaviour
Researchers have no idea why they hunt the birds but speculate it could be because of declining prey

The term 'a fish out of water' describes someone taken from his natural environment to one he's not comfortable in.

But a group catfish in one odd ecological pocket have shown themselves to be rather comfortable with leaping on to dry land.

A study published yesterday investigates the remarkable phenomenon of the catfish that hunt pigeons.

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Lying in wait: A catfish lurks in the waters of the Tarn River while it waits for a pigeon to stray too close

Pounce: The fish lunges from the water and snaps up the bird in its jaws

Catfish in south-west France have been spotted leaping from a river to snap up the unsuspecting birds, before wriggling back beneath the water to swallow them.

The unusual behaviour - similar to the way some marine mammals beach themselves to snap up prey from the shore - has never been seen among catfish in their native range.

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It has led researchers the University of Toulouse to dub them 'freshwater killer whales'.

Between 1m and 1.5m long, European catfish are the largest freshwater fish on the continent and third largest in the world.

Most catfish are bottom feeders, consuming aquatic plants, other fish, decaying vegetation, fish eggs and crayfish as well as snails, aquatic bugs and minnows.

Feeding ground: Researchers spent five months watching the catfish from a bridge over a small gravel island over a stretch of the Tarn passing through the city centre of Albi, north-east of Toulouse

However in the Tarn river, where they where introduced in the early Eighties, they seem have adapted their natural behaviour to capture prey in their new environment.

Researchers spent five months watching the catfish from a bridge over a small gravel island over a stretch of the Tarn passing through the city centre of Albi, an ancient town about 50 miles north-east of Toulouse.

Over that period they observed 54 beaching incidents, in which the catfish managed to snap up a bird 28 per cent of the time, dragging them back into the water to gobble them up.

While the beachings were quick - lasting from less than one second to no more than four seconds - in about 40 per cent of cases the fish lunged so far from the water that more than half their bodies were exposed.

Just when you thought it was safe: In five months they observed 54 beaching incidents, in which the catfish managed to snap up a bird 28 per cent of the time, dragging them back into the water to gobble them up

To go back in the water: The beachings were quick, but in about 40 per cent of cases the fish lunged so far from the water that more than half their bodies were exposed

Along comes a hungry catfish: The unusual behaviour - similar to the way some marine mammals beach themselves to snap up prey from the shore - has never been seen among catfish in their native range

Catfish are named for the long, sensitive whiskers (known as barbels) around their mouths, and the those of the Tarn fish would perk up whenever they were hunting fish.

That finding, combined with the fact that the fish only went for those pigeons who were moving, suggested the the catfish used water vibrations to hunt rather than visual cues.

While the study highlights an interesting example of unusual behaviour, the researchers said the ecological causes that have led to the unusual adaptation are still unknown

Catfish were only introduced to the Tarn in 1983, and they now flourish there, leading the researchers to speculate that increased numbers of the fish could have led to a decline in marine prey.

The findings were reported yesterday in the open-access journal PLoS ONE.