Well my tanks are much larger so I have a little more "wiggle room," but for you i would reccomend a few hermit crabs (4-6), a few snails (4-6), and a cleaner shrimp or two. Don't add them all at once, add a few each weak and let them cycle the tank. The cleaner shrimp should probably be the last ones in the tank since they are the most delicate. For the snails, if your planning on making it a reef tank there are a few you should avoid, but otherwise you have a huge selection of snails that will add lots of color to your aquarium along with cleaning it. Remember, you will still have to feed the tank since it is new and theres probably not much food in there for your CUC to eat until the tank becomes more cycled. If you enjoy the hobby so much (which you will), you can get larger tanks and the CUC becomes much more exciting. It amost seems like you don't nee fish! In my 75 non i have at least 10 different species of snails, 5 different species of hermit crabs, 3 emerald crabs, a sallies lightfoot crab (who was naughty and now lives in the sump), a horshoe crab, 2 starfish, 2 sea urchins, and who knows what else! For my 90 gallon reef i have mostly the same stuff minus the things that eat corals, but I have live corals! Also with a reef tank i am able to have things like anemones, feather dusters, clams, etc, and you could to! Wow I just went way off topic but I'm to lazy to delete it so enjoy! I hope I helped your decision (waaaaay at the top)
