I wouldn't even keep one in for a year. Remember the whole purpose of this is to let the animal thrive and be healthy and happy. I would highly recommend you upgrade before you get the shark. Speaking from experience, I had a baby port jackson in a 55 for a year. It was heart breaking to see such a incredible animal in such a small tank. I did put him in a 320, but the damage was done. He wasn't very healthy by time the 320 cycled and only lasted a couple of months. This is just my two cents, but I hope all the folks out there that are thinking of upgrading after you get your shark will rethink the order you do things. You'll find that most of the sucesses you read about hear are because the environment is established then the fish is introduced. Sorry to ramble on, but it seems to be a common plan to buy the animal then build the home. HTH