When he gets bigger, are you going to put a swimming pool in your back yard for him?
It would need to be one huge swimming pool. An adult will need an enclosure about 100' X 50' X 30' or 1,122,069 gallons. It is very sad to see animals like this sold to aquarium hobbyists as there is no way they can care for them. Many European countries are passing laws against such fishes being offered for sale. I am not sure that I like that solution, but putting the burden on the hobbyist to do the research before buying an animal they can not possibly care for is not also not working very well.