With silver aros you can go with a wide variety of tankmates. I have my silvers with Red bay snooks, misc catfish and loaches. My black aro is housed with discus and some loaches. As you may have already read, your 180g is eventually gonna be to small, but would be a decent size for quite a few years. If you plan to eventually upgrade to at least a 300g wide(96" x 30" x 24") I would definetly recommend getting an aro they are great fish.