Wildlife experts have called in the police to investigate the sudden appearance of a number of goldfish at Lingfield Nature Reserves in Surrey, where the ponds are home to protected Great crested newts.
The goldfish are thought to have been introduced by a member of the public about two weeks ago and are around 10-17.5cm/4-7" in length.
Experts say that the fish will eat the larvae of the newts, as well as dragonflies and other species and if they breed they could cause "irreparable harm to native wildlife".
Lingfield Nature Reserves management committee member Ray Baker said: "The newts go into the pond this time of the year to breed. Most of the year they live outside the water, so this is the worst time of the year for it to happen really. With the number of Great crested newts we have, ours is a site of national importance."
The matter is under investigation by Surrey police and the culprit could face criminal charges if caught.
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