i have an oscar on a 55 gallon only about 6 inches big with tail.It has killed a convict which is about 2 inches when it was 4 inches a dempsey that was 2.5 inches when it was 5 inches big. now i want to add a red devil because im getting a tank in the summer early june. the red devils at petsmart are what im looking for because (correct me if im wrong) about 7-8 dollars only (canadian) the midas/red devil. but i heard bad stories about red devils but im still worried that my oscar will kill it. is it recommended that i try it or not. because i cant wait to have a red devil