This emerald crab (M. sculptus) appears to be interested in bubble algae, but that’s not the case for all specimens.Among the various and sundry marine life commonly sold to aquarium hobbyists for utilitarian purposes is the emerald crab (Mithraculus sculptus). Oft touted for its propensity to gobble up bubble algae and other irksome algal forms, M. sculptus has become a proud, card-carrying member of many a marine aquarium “cleanup crew.” But before adding this “benign” crustacean to your aquarium to control algae, be advised that it may not be as strictly herbivorous or reef-safe as you’ve been led to believe. Physical traits Aptly named for its shiny, emerald-green overall coloration, this Caribbean species reaches only a few inches in diameter and has a bumpy carapace, hairy legs, and relatively robust (for its size) claws. One could argue it even looks rather like the bubble algae it supposedly consumes with such enthusiasm. About that bubble algae thing… If you’re adding emerald crabs to your system in the hopes of eradicating a major outbreak of bubble algae or any other form of algae, you might be disappointed in the results. Not all specimens eat troublesome algae forms reliably, and even if they do, they may not eat enough of it to bring a severe outbreak under control. Some years ago, I added a group to my 75-gallon reef tank when it was in the throes of a bubble algae plague, but they never really made much of a dent in the problem (it took a lot of handpicking and water changes to restore sanity) More: Does the Emerald Crab Earn Its Algae-Eating, Reef-Safe Reputation?… More:
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