Just FYI, the jawline idea, this is striclty muscular, there is no skeletal difference from a male to female. So even a male may appear to have a smoother jawline. Not always accurate. But introducing a male to a female may intice the male to "poof" up his jaw to impress the ladies. Best to start to with a small aggregate of juvi's and weed out a pair once it forms. If they are older bangaii's, find a comfirmed male bangaii and stick one at a time in with him, you should see failry quickly weather or not he's attacking the new male you stuck in, or if he's checking out the female. Bangaii's tend to have a 1male:1female ratio with their offspring so odds are a group will yeild at least one pair. Bangaii's also can have incompatible pairs, where a male just doesn't like the female or vise versa. So if he's ignoring the new addition completely or chasing her off, may just have to keep trying.