I used to have a Niger that would do the samething. When I turn on the lights in the morning, it takes him about 5min to come out after the lights are on. But if I walk too close, he'll be back in his rocks in no time. Then I just put some food within then walk away, when I come back, he is out and about eating. Try feeding it with live brine shrimp at first to get it to start eating. Mine eats the flakes too, but he died one day for some reason. I find the Hermit Crab eating the rest of him. Do not know what happened! Everything in the tank was fine and the other fish was fine. Anyway, we then got a Humu Humu Trigger that died within 2 days, bad batch, he wouldn't eat anything I give him and hides all the time, not even live brine shrimp. We then got another one about 2 weeks later and I found out that they were feeding them feeder fish, the one before also. Bad thing they only had'em on feeders. So I bought some to get the Humu Humu start eating for me. Once it starts to feed, I then try other food and she takes whatever I give her. I feed her Formula 2, Formula for Triggers, Blood Worms, Live Brine Shrimp, and as a treat once in a while, feeder fish. I had her for quite some time now and she is doing very well and growing!!! At least this one don't ever hide when I'm around instead he'll come right up to the top and eat from my hand. :happyfish