Angelfish will eat neons if you're not careful. It might harass fish that are too big to eat, but it varies from fish to fish. Mostly, I would be careful with barbs, serpae tetras, and other cichlids (dwarf cichlids should be fine, be very careful with other angelfish). You might be fine with neons if you put the neons in first, let them grow a little, then got an quarter or smaller sized angelfish and let it grow out with the neons. But, your mileage may vary. Doesn't always work.