yeah hes kinda aggressive. i believe he killed a couple peppermints. he also goes after fish. hes really my bf's so i told him that we had to get rid of him, hes just got too mean, well now he wants to set up a whole tank just for him. LOL. he said we had him since he was a baby, and we watched him grow and he didnt want to get rid of him. so, a 20 gal just for him will be put up this weekend. LOL.