sexing red jewel cichlids.

Look for the biggest most colorful fish in the tank (the one that is holding a position and chasing others away). That's the male. Now look for a fish that might move around the tank, but is NOT chased by the male. That's your female. That's what I did for rams, but for Jewels I don't know. The behavior should be similar though.
 
I found out what type of fish the lfs has. It is Hemechromis lifalili. (blood-red jewel cichlid) Or at least that what he buys, but we think he has kind of a mix, because we notice that he has some that's colors look more like some of the other species. Will they interbreed? Like a lifalili and a fasciatus? I'm probably going to get 5 or 6 and try to get a couple to pair off.
Also, the jewels at my lfs are about 3 in. already, and I want to put a dempsey with them, but I want to get him at around 1 in. Will the dempsey be able to hold his own if he's that much smaller?
 
AquariaCentral.com