I have read alot on it and think the general consensus is that it's hard to sex them when they're so young and not old enough to be vented yet, but i still wanted to get some people's opinions. The ones in the first two pics are together a bit more and the acara in the third pic is more territorial/aggressive and chases the first two. I'm not sure if it's because the first two are paired off or if they're simply sticking together just because they're afraid of the slightly bigger #3. Judging by the dorsal fins i think acara #1 and 3 are males and 2 is a female but I can't be sure because they're only like 3 months old. I'm waiting to be sure 2 have paired off before i move the 3rd. Thank you!