the males are great, not so keen on the females. I get lots but have real problems selling or even giving them away! I keep them only to encourage plecs to breed -lol.
well the theory is that breeding fish (guppies, cories etc) when breeding release pherimones or hormones of some type which are detected by other fish and helps tell them its the breeding season.
My L104's bred right after the royal whips in the same tank did.
Keep the endlers in a few tanks. I found mine ended up inbreeding quite quickly in one tank.