Red Emerald Crab
Mithrax crabs possess dull claws that enable them to scrape algae from liverock and are effective at eliminating bubble algae, hair algae, Dictyota, some species of Caulerpa, and other intricate macroalgae. The severity of your bubble algae issue will primarily dictate the number of emerald crabs needed to accomplish the task. These crabs are omnivorous and will also scavenge for food. They tend to cling to hard surfaces, where they can spend their time.