These little guys are round gobies. an invasive species in lake Erie and according to the wildlife organizations and such i have read about then from if caught should be destroyed. Though considering how many i saw there killing the five i caught would be about as useful as trying to stop a tsunami by tossing rocks at it. At anyrate i am "punishing" mine with "jail" time in a nicely appointed tank with food and exercise opportunities but they get no cable or internet access and will be restricted to basic schooling (hah schooling i kill me!)