Had a mature (3-4" diamond goby for about a week now. From a reputable LFS. It has been eating like a pig (flake/frozen/mysis). It has not been harrassed by anyone on the tank. Noticed it ate yesterday morning,but has not came out since. Lifted up the showpiece rock it was burrowing under and it was dead. It had a pink offcolor spot in its belly. The only thing I can think of is Bristleworm-but wouldn't they eat the whole carcass? 210 gallon reef tank. No other deaths, corals are all healthy as are fish/inverts. Params are great. Any idea-really wanted him for my tank. Kinda leery of getting another.