As far as actually depleting the sandbed of life is a bit of an overstatement. They will eat some of the microorganisms, but certainly not all. Many folks keep them in their reefs with no problems. Now the yellowheaded or blue cheeked goby is far worse. Not only will it deplete youe sandbed of life, but as it grows it will do other strange things. I have a friend who has two, and it depleted his tank of hermit crabs. His gobies liked to collect them and put them in burrows and holes in the rock. That is where he found them when cleaning his tank.
