First off Welcome to the boards! Second I would reccomend posting in the "New Hobbyist" forum, since the "Aquarium" is for non fish topics. If this is your first tank, I would say just start out with some hermit crabs and snails. They are the cleaners that everyone needs, then later on get some more. All triggers are agressive and will pick off any smaller fish. Since some of your fish will stay on the smaller side I would say no on the Niger. Also damsels can be a real pain, since they get fast, mean and some get big. If you can, I would reccommend taking them to an lfs and trade them in for somthing else. Hope this helps and good luck with the tank!