I have a 20 gallon cube aquarium, dimensions are: 17.7 x 17.7 x 15.7 inches. I am struggling to figure out how much can go in the tank. I definitely want a clownfish pair and a royal gramma. I also want a cleaner shrimp, some hermit crabs, and some snails. I really like gobies and wanted to get one or two to put in there but I don't know if that would be too many fish to put in there.


