I have seen Lemon Sharks in the wild while diving in the Bahamas. These sharks were 6-7 feet in length and "very" active swimmers. This is not mention their aggressiveness.
A shark this size would need a Sea World size aquarium to thrive in. I have also seen many Nurse Sharks in excess of 8 ft.
I know there are fish stores that sell these animals, but it is IMO
extremely irresponsible to keep them in captivity in an a tank less than 10s of thousands of gallon.
I realize that Nurse Sharks do spend a lot of time sleeping on the bottom and seem rather lazy. Don't let this fool you, they also spend lots of time swimming in search of food, much of it at night. It would be cruel to keep them in any size home aquarium, simply not enough room for them to thrive. Like living in a closet.
What would one do "when" it outgrows the system? Offer it to the local zoo? What if they don't take it? Its a condemnation for these animals when we buy them, it give the industry reason to keep capturing them for people with insufficient systems to properly house them.
Sorry for the rant, but it makes me a little nuts to hear of people who "think" they have a large enough system to house sharks when in reality a shark need more room than most of us can ever offer. The ocean is being depleted of these magnificent animals as it is for soup and other BS. Lets let our community of caring hobbyists encourage our local fish stores to leave them in the sea where they belong.