We had a diamond goby (sifter) in our 75G. It jumped a couple of months ago :( , but prior to that, it did a good job of keeping the sand clean. The only thing I didn't care for, is that it was always trying to cover our Hawaiian featherduster under a lump of sand...the featherduster just happened to be right where the goby decided to dig it's cave. They will dig under rocks, move rocks and frags if they are small enough to pick up (you'd be surprised what they can lift!) if they get in their way. We almost had a rock slide once because of him...they are very industrious/active diggers! I doubt seriously we would ever get another one. Once they are in your tank, you'll have a heck of a time getting them out too...FAST little buggers! Personally, I'd stick to nassarius snails to keep your sand bed clean....or a cuke'/snail combo. JMO ;)

Wendy