Klongo, You do have to find a pair that have already paired up. A LFS near you should help you out. The LFS near me got me a pair by just waiting until they came in, waited a week or so to see them mate up, called me and that was that. They had many babies and the babies would go through the out take pipes into the bottom tank and I would raise the ones that would survive their ordeal, 5-6 months later, sell the babies back to the LFS. They survived nicely in the sub-tank.
The male does carry the babies. Very interesting. They do eat peppermint shrimp, so if you ever have a problem with aptasia, you will need the shrimp. In a tank your size and plenty of hiding places, the shrimp would survive long enough to eat off the aptasia. I have the shrimp just for enjoyment now since all the aptasia are gone but for years had to keep buying shrimp and realized it was the Bengaii's. My LFS suggested that was what was happening and indeed they are night hunters and they were capturing the shrimp. But, they are very enjoyable and different. Good luck.