Festae usually start to pair out around 4.5-5" although I've had some pair out around 3.5-4" but that was from a large group and they formed on their own.. Completely out of my control lol as long as you have a group, you should eventually end up with a pair
just keep a close eye on them and look for signs of pairing good luck. Sent from my iPhone using MonsterAquariaNetwork app
