any type shark you plan on keeping if you want him to be healthy and live a full life will require a 300 gal minimum tank.one thing to concider before purchasing a huge tank and a shark is if it does grow to be full size do you get bigger tank for him? can you afford a larger tank for it?if your answer is no to either one of these questions you realy should reconcider your thoughts about purchasing a shark.next if your answers were no to either of these question and you still think you should try .concider what your going to do with a 4ft+ size shark when you have no room for him anymore.most pet stores will not take them , they have no place for them either .most aquarium exibits will not take them either so what do you do with a shark that has outgrown your home.just food for thought..and yes I know exactly how you feel about this I have ben going through this same debate with my hubby for the last 2 yrs he gave up his fight when our local fish store told them if he buys a nice looking shark from them when it gets too big they cant take it back.