Scientists have put some robot fish into the sea near Spain.【小题1】 So far，the robot fish have managed to finish their work，and the scientists hope the fish will be used in rivers，lakes and seas around the world.

The robot fish are about 1.5 meters long.【小题2】 They can find the pollution in the water，and then the robot fish will eat part of it.

Unlike other robots，they don't need to be operated（操作）by people far away.【小题3】They can “swim” in the sea freely and send back information to people on the bank. When their batteries are used up，they'll go back to the bank themselves.

There are five robot fish.【小题4】They're a part of a three-year plan of the engineering company BMT Group and Essex University in southeastern England.

“We hope the robot fish can find the changes that have taken place in the sea water and send back the information to people，”said Professor Hu of Essex University. His team is developing the robot fish.

【小题5】