My tank is fairly small (Red Sea Reefer Nano). 21 gallon display with 6 gallon sump. I have some algae in the DT that is a bit too big for the standard CUC crab. The algae problem isn't that bad as my entire sump is a big refugium powered by a Kessil H380, but still there are some patches and they're growing slowly so I want to get ahead of it. I don't want to feed less (I feed the fish once per day and the corals twice per week) as my SPS coloring loves having some nitrates in the water. I've been thinking about getting an emerald crab to go after this algae, but my research on how safe they are has been very inconclusive, which is why I want to do the poll. I have two clowns, 1 helfrichi firefish, and 1 Biota captive-bred Mandarin from AlgaeBarn (don't worry he eats prepared foods and is the fattest fish in the tank ). Having said that, these are all small fish. I'm not too worried about the clowns, but the firefish and mandarin sleep in the rock work and I don't want them to fall victim to the emerald. Thoughts?