In the past 3 months I've had several fish disappear from my 100g reef tank. In addition to fish, the tank has a porcelain crab, several conchs, two small anemones, a 1" sand substrate and about 60 pounds of dry rock. Surviving fish are angels, a blenny and one clownfish. MIA are three 2" angels. I've searched everywhere for them, including the sump and floor around the tank. No dice. Any suggestions appreciated.