keep in mind that many fish are kept both brackish and fresh. bumblebee gobies and mollies are perfect examples. make sure that when you decide on what you want, that your lfs sells them as brackish. if they sell them as fw, you'll need to keep them in fw as they won't acclimate well. i keep my mollies fw, as thats what the lfs sells them as, and they do fine. same with my future bb gobies. some puffer types are indeed brackish, but there are fw varieties, like the dwarf ones, that are fw. check out the oddball section for more on puffers. are you interested in any fish in particular or do you just want a brackish tank and aren't too particular about fish types? do you currently have mollies that you keep brackish and are looking for ideas for tank mates? that will help us to give you better advice........