A 25lb catfish was caught at the man-made lake at the Lakeside shopping centre in Thurrock, Essex.
Officer Ben Norrington said: "Large fish have the potential to eat wildfowl so we're pleased we could remove it."
The EA said the animal had been seen eating ducks!
"Invasive species pose a serious threat to our native wildlife," Mr Norrington added.
For more on this story check out today's bonus segment with Len Bernman and Michael Riedel...