Hey guys trying to do the right thing here before i go out and just buy fish. Im thinking about geting a baby clown knife and a baby silver aro and putting them in a 72 gallon GROW OUT tank that's 18'' wide just wondering how long i can keep those two fish in there before i upgrade now keep in mind i dont plan on "power" growing these fish they will be fed a good balanced diet every few days. Now my next question is what is the min tank i need to purchase for these two fish to live togther in comfortably long term. thanks ahead of time for the response