I have a a few tanks of african cichlids and this guy was on my filter just watching the new fry i have. For what ever reason, i can handle scorpions, rattlesnakes and even tarantulas but cant handle little guys like this. haven't killed him yet seeing as how the black widows and brown recluses are the real dangerous ones and don't feel a need to dispose of it. curiosity got to me and wanted to know what it was. any takers? Id say aggressive but wouldnt you be if there was a giant flat head screw driver trying to put you in a Tupperware container?