An introduced species of North American catfish has been recorded in the wild in the UK for the first time.
According to a paper in the latest issue of the Journal of Fish Biology, the catfish, which has been identified as an albino White catfish, Ameiurus catus, was caught by an angler at Epsom Stew Pond, on Epsom Common in Surrey in southern England last August.
The fish, which measured 62cm/24" in length and weighed 4.55kg/10lbs, was originally believed to be an albino Channel catfish, Ictalurus punctatus, but closer examination of the fish showed that it was actually the less common Ameiurus catus. It is the first time the fish has been recorded in the wild in the UK.
The authors of the paper, Britton and Davies, believe that the specimen is a discarded ornamental fish:
"As albino I. punctatus specimens are available from North America as ornamental fish, it may be that this fish was imported mistakenly as this species and sold to an aquarium or pond owner, who subsequently introduced it into the lake, perhaps as it outgrew its surroundings.
"No other A. catus specimens have yet been recorded from the lake and there are no records of the species in any other waters in Great Britain. Given that a common introduction mechanism for non-native species is the discard of unwanted ornamental fishes, then the possibility remains that other specimens may be present in the wild. Should this be the case, then further establishment in Great Britain may be hindered by the temperate climate. This would inhibit reproduction, as it requires temperatures above 21C."
Ameiurus catus is native to the freshwater rivers of the eastern USA from New York to Florida and can reach a length of up to 90cm/36".
It is not a common species in the aquarium trade and trade in the species has been restricted for several years under the Prohibition of Keeping or Release of Live Fish (Specified Species) Order in 1998, which is part of the Import of Live Fish (England and Wales) Act 1980.