Ok I have emerald crabs and they don't eat the bubble algae I have. Mine is not spreading and is slowly dissapearing. Keep your water quality up. I never starve my fish; I feed them once every evening. The thing is you can feed daily just reduce the amount. Do you think fish in the wild only eat everyother day? I personally feel if you do not feed daily you stress them out. I tried it for a few weeks on another tank and my tangs got lateral line disease. As soon as I went back to daily feeding and adding vitiamins to the dried algae strips it went away. Back to the crabs, emerald crabs are tiny! They would have to pop the bubbles to eat them, they do that they release more spores! Do you test for phosphates?