the one you see as my avatar was out in top of the substrate and in full view under a metal halide light. I basically had it trained to open when I turned on the lights in anticipation of food. I'd feed the fish first so the food in the water would get it all open and then I'd target feed the sun corals polyps with a turkey baster. I used a mix of mysis, carnivore & omnivore foods, cyclopeeze, flakes whatever I had grabbed to mix up that moment, and I also had some marine liquid vitamins I would squirt in the mixture. I had a cleaner shrimp that would rob the sun coral, but I'd stand by and squirt him with food and water and shoo him away. I was a bit obsessive about that coral. :grinyes: I plan to have another one in this tank I'm working on, but I won't have a cleaner shrimp. Annoying little buggers! Anyway, I probably fed heavily enough, it didn't seem to be harmed by whatever did get stolen from it. I fed mine twice a day though, same time I fed the rest of the tank. YMMV