A walking catfish has been spotted in the Thames by an angler.
The air-breathing fish, which can survive out of water for 'extended periods' as it searches for water, was found in the Thames Estuary at Woolwich by angler Birol Koca.
Mr Koca immediately phoned the Environment Agency who sent an officer to the scene to confirm the find.
The walking catfish, or Clarias batrachus, is a species of freshwater airbreathing catfish found primarily in Southeast Asia.
The fish, which could be a 'significant risk' to the environment, used its pectoral fins to 'wiggle' on land as it searches out a new home.
Catfish can pose a threat to the environment if they escape into the wild by competing with native fish for food and habitats and spreading disease or parasites, the Environment Agency warned.
In Florida the fish has become a 'pest' after it was brought over from Thailand in the 1960s.
Residents of the US state regularly have to stop cars to wait for huge 'shoals' of the fish to pass as they shuffle along the road looking for water.
Mr Koca said: "I spotted the fish laying on the shore and instantly recognised it as a catfish.
"I knew that these fish should not be in our local rivers so I called the Environment Agency's 24 hour incident line. It looked dead, but I wanted to make sure."
Fisheries officer Emma Barton said: "Non-native fish can pose a significant risk to the local environment.
"The local angler acted very responsibly. By working with us, they have helped ensure that the Thames and the wider environment is protected. We urge others to do the same."
She added: "This species which is native to South East Asia has the ability to walk over land using its stiff pectoral 'spines' and a back-and-forth movement of the body.
"It also has an air-breathing organ which functions much like a lung when it's on land."&£8232; It is likely that the catfish was illegally introduced from an aquarium after it grew too large for its home.
Local Graham Telfer, 32, said: "Let's hope this isn't a sign of things to come. The last thing we need is a bunch of walking catfish taking to the streets.
"Hopefully we've caught this in time and we're not going to face an invasion of these bloody things."