Monster or not ?

Question

could anyone tell me i got quite excited thought there was a frog in my pond, sadly not it is a great diving beetle but ok still excited.

problem is would he be a bit of a thug and kill of anything else that trys to live in there he does look a bit ferocious :-)

Answer 1

They will eat small fish and tadpoles

Answer 2

As twells says,they will eat small fish and Tadpoles. The larvae are equally ferocious, and will attack tadpoles and similarly sized creatures with ease for the year that they are in that stage of life.  

Wildlife they might be, but exclude them if you can from your pond if you would like to see other life in your water!