food, they eat planktons and some of the debris from the fish food
fish selection does matter, some fishes will eat them
substrate doesn't seem to make a big difference, ours is on the glass, sand a nd rcok
temp high 70's
salinity, ??, let me look, my reference says 1.023 to 1.025, we have colnies, and ours are in 80 degrees, with 1.025,a nd no predatory fish, we did however have a problem with a peppermint shrimp, which as i understand it is a reak thing(they normally don't bother feathers)