It really does depend on the personality of the specific fish. If you really want to add one, you must really upgrade your tank in about a year ish. Most people expect to upgrade then when the time comes, they don't have the money/time/effort to do it. there are always exceptions, of course myself as an example. I would have set up a 100+ to begin with but I had to move into an apt. before my husband got back from overseas until we bought a house. Now doing a 150g with 4 triggers, 2 maroon clowns, 2 pyjama cardinals, and a huge onespot foxface. (also gonna add a red coris for some sand fun) Whichever way you choose, GOOD LUCK