Crucians back in big numbers

Rare pure-bred crucian carp have been stocked into a Norfolk fishery.Three thousand of the fish, reared at the Environment Agency's fish farm at Calverton, Notts, have been stocked into a gravel pit near Lyng to establish a breeding population of the species.

Rare pure-bred crucian carp have been stocked into a Norfolk fishery.

Three thousand of the fish, reared at the Environment Agency's fish farm at Calverton, Notts, have been stocked into a gravel pit near Lyng to establish a breeding population of the species.

True crucian carp have become increasingly rare because they interbreed with feral goldfish and common carp, which have been widely stocked in many lakes for angling.

There are few waters left with pure strains of the species and they are thought to be almost extinct in Norfolk.

EA fisheries expert Adam Piper said: “We chose the lake because it does not have any common carp or goldfish in it, so the pure-bred crucian carp population should be maintained.

“We hope this will establish a successful population in Norfolk that will become a source for stocking suitable waters elsewhere in the county.”

Crucian carp are a very hardy species of fish which can survive in temperatures almost to freezing and as high as 38C.

They rarely grow above a couple of pounds but are tolerant of low dissolved oxygen levels and can live where many other fish species cannot.

Pure-bred crucians are notoriously difficult to identify from hybrids, and any records of their presence need to be carefully checked.