Before you have a 28 Days Later moment, take a deep breath.
These tiny crustaceans, the Dikerogammarus villosus shrimp, which can grow up to 3 centimeters (about 1 inch) in length, pose no direct danger to humans.
But the killer shrimp is bigger than local species – and more aggressive.
The "killer shrimp" eats other shrimp and small fish that are common across the UK. Like the Asian carp in Lake Michigan, the species is not native to this part of the world and may cause problems for the UK's water ecosystems.
"It tends to aggressively pursue its prey, often leaving it dead but uneaten. It is known to have caused the extinction of several other species in other areas," the Epoch Times reported.
Not only is it bully, it has few predators in this new habitat.
The "killer shrimp" has three spikes on its back, making it inedible for small fish who choke on the prawn when they try to swallow it.
Scientists are now testing the water to see how widespread the "killer shrimp" problem may be and have put up posters warning boaters to check their equipment and vessels in an effort to stop the potential spread of the species into other British waters.