Recommended for a 10G + aquarium. You need a good amount of rocks and coral so they will be happy. If you don't do not attempted to keep one. They are Carnivores and will eat any meaty thing that will fit in there mouth. I had three in my 150G reef. Great fish. Will spend a lot of time in the rock's and coral. A few friends tried them in FOWLR and they didn't last very long.