hello it is a rather difficult task, the emerald crab ( Mythrax sculptus or sp.) readily eats it but you have to keep an eye on the bigger specimens as they remain opportunistic. the one thing not to do is to pierce the bubbles otherwise the spores will spread in the tank more again
yes they should. be careful to pick a reaaly small crab, it can take its time to feed on the bubbles but it usually comes to it one day or another. The esmerald crab may lead to problem with corals instead, particularly softies such as Sarcophyton sp. as the crab may feed on the mucus and thus troubles the polyps. really bigger crabs may be a danger sometimes to really small, slow fishes. But on regular basis, always keep an eye on any crab and feed it if necessary as they may become used to it. I have a rather "big" red Trapezia sp. in a Stylophora sp., and I have taught the crab to come outside the "bush" and get its food whenever I am feeding the rest of the lot.
Hi, for what it's worth I have a Emerald crab in my tank now for seven months and no bubble alge, and for me personally it has been ok. But I have read that they may or can cause damage to soft corals, as of yet I have had no problems with it.