The unusual find on the Grand Union Canal is believed to be either a white or channel catfish from North America.
It was in Grand Union Canal’s Stoke Bruerne to Cosgrove pound in Northamptonshire.
The Canal and River Trust captured it after reports of an angler catching and returning a very similar catfish.
John Ellis, CRT national fisheries manager, explained: “It was the only one we caught but a few days earlier an angler caught one in that locality.
“The angler returning it would have technically committed an offence under law.
“As required, we reported the find to both the Environment Agency and Natural England.
“As we can’t be sure it is the same fish, we are seeking advice from the regulator as to whether they deem it necessary to search for more.
“This sample was dispatched and sent to the EA lab at Brampton for analysis.
“We expect this is a rogue fish that was improperly released into the wild by its owner when it got too big for an aquarium.
“It is extremely rare to come across unusual specimens but we did net a South American pleco catfish (pictured below) about 18 months ago during a fish rescue on the Walsall Canal.
John continued: “I can’t think of an obvious single example where the release of a non-native species outside its natural range has proved beneficial to the ecology of an aquatic ecosystem.
“Anglers are reminded that it is an offence under section 14 of the Wildlife and Countryside Act (1981) to return non-native invasive species such as catfish and zander to a canal,” John concluded.
If the Grand Union Canal find is a white catfish, it would be only the second time one has appeared in the UK.
The first one was back in 2005 when an angler captured one from Epsom Stew Pond in Surrey.
Fortunately, there is little danger of the species establishing itself here as it requires water temperatures consistently above 21C in order to breed.
Channel catfish are more hard as they come from the cooler Canadian/USA border.
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