I house my full grown pac man and my F/ dwarf pixie together in a large tank they are not aggressive rather they are buddies the dwarf will try to sit on my pac man or right next to him they chase each other around idk my pac man is a wuss and my pixie has a pretty small head which it would be impossible for her to eat him she could nip but like i said i see no aggression towards them and they have lived together for about a half year but in your case having a giant mixed in would not be a good idea.