Amphilophous nourisatti

Picked up an 8" male yesterday, he's currently in QT after which he'll be moved into his own 90 gallon.

Can't find much of anything in regards to husbandry or even how to tell between the sexes on these guys, so any insights are appreciated.

So far he's very shy and sulking, I think it's a result of being in a bare bottom tank for the time being - hiding behind a sponge filter any time I come into the room.

I put 8 long fin black skirt tetra in the tank to help coax him out, but it's not working so far, very timid fish but it's expected in a transition.

Anyway, to those of you with a bit more experience in the realm, I'd appreciate any information on him.