A Rottweiler is only the way its behaved is the way its been brought up, i know from experience. I had a Rottweiler and she was so cute and wouldn't hurt a fly unless she saw someone was hurting us or they hurt her and believe it or not everyone was scared off her unless we told the person that she wouldn't touch them. Guppies, and yes the idea is to get 5 males or 5 females not a male and a female if you don't want to be cruel.