Some of the fish will be released back into the Kennet and Avon
More than a tonne of fish is to be removed from a section of the Kennet and Avon Canal to help improve conditions for aquatic wildlife.
The "abnormally" large number of fish have been left undisturbed for several years, according to British Waterways.
Some will be taken from the side ponds of the Caen Hill lock flight near Devizes in Wiltshire and relocated.
The fish have been stirring up the silt making the environment less suitable for some insects and plants.
Dragonflies, damselflies and a number of scarce aquatic plants rely on clear water environments.
The stirring up of silt, caused by boat movement through the locks and fish feeding on the bottom of the ponds, has caused the growth of algae, said British Waterways.
Ecologists, coordinating the work, expect to find large tench, carp, bream, roach, perch and pike, as well as eels.
Water in the side ponds will be drained down to about two feet, and nets will be used to trap the fish.
The fish have stirred up silt in the side ponds of the Caen Hill lock flight
A proportion will be transferred to other canals, including the Grand Union near London.
Some of the catch will be released back into the Kennet and Avon Canal below the lock flight, allowing local anglers a chance to fish for them.
John Ellis, fisheries manager for British Waterways, said: "Anglers love the excitement of seeing if they can land a really big carp and this fish operation will certainly bring some weighty specimens to light."
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