These guys top out at over 4 inches, so a 10 gallon would be on the tight side to say the least. Beyond that, they're pretty strongly predatory, so small guppies and their fry would be fair game as far as their diet goes. Breeding might occur in a 10 gallon, but it seems unlikely that many fry would survive predation in such a small space. If you're really interested in this species, I would not recommend keeping them in anything smaller than a 20, and using the 10 specifically for breeding purposes. If you condition the female separately in the 10 for a week or two before hand, introduce the male, leave them for a week, then remove them, they should leave you with enough eggs/fry in the tank to raise a nice batch of youngsters. Thickets of java moss or yarn spawning mops would both be excellent choices of spawning medium.