i just got mine a few days ago and ever since, he has been hiding in the back of the tank, he'll come out now and then but he won't eat anything. i've had brine shrimps along with mysis float right by him. should i start to worry? also, how safe are these guys with corals, i have some zoo's in the tank. i've been told they're 50/50 as far as reef safe, but more feedback would be great.