i had started a plan when he get older he will be move to the 50 gallon but then i forgot the red-tail shark was in the 50 gallon so i knew the shark will pick on him so i dont about the 50 gallon.he will Defiantly have a pond(my turtle will have to live in the pond when they get bigger) my goal is to get a 400 gallon pond in the future I read that koi will need 1000 gallon pond from live aquaria I’m not sure if I will have room for a 1000 gallon pond in the backyard. the shed took most of the space of the backyard