Will lepto's eat fry?

Cyprichromis leptosoma aka "cyps" will eat fry occasionally, but they're aren't likely to going hunting for fry very often. I'd be more concerned with the brevis eating their own fry when they get ready to spawn again.

Not really... You could consider Paracyprichromis for that tank. Or, if you haven't bought the tank yet, perhaps get a 48" long tank instead. :thumb:

Cyps can live in 36", but you won't see the same schooling/territory behaviors and may have trouble with aggression among the males.

Your best bet for protecting brevis fry is to move them to their own 10 gallon tank after they are free swimming. If you want a community tank, you are going to lose some fry. Even the most peaceful vegetarian cichlid will eat fry when given the chance. It's a tradeoff: more fish = lower fry survival. You can make choices for less prey-driven fish to even the odds a bit.

Some species that would be good with brevis for a 36" tank :

Gobies (Eretmodus, eg)
Small Julidochromis (not marlieri or regani)
Paracyprichromis

HTH