Thanks, I made a decision that I WILL do LOTS more research before even attempting sharks, as I don't want to make a mistake of a small tank that will end up hurting the shark. What size is your aquarium and what types of sharks do you have? Since I don't have nearly enough money to build a 30 feet tank, do you think that down the road I could keep a BTRS in a smaller tank just for a while, and then when it's grown the tank out I could sell it? I'm wondering till what size I could keep it in a 9 feet long tank?