btw, my nurse shark didn't die because it was cramped in the 200 gallon tank.
The guy I bought the tank from had cancelled his LFS maintenance agreement some 7 months prior to selling. In this time, the tank had not been cleaned or touched by the owner. The salinity was 1.016, pH = 7.5, nitrates were over 2500 mg/l, and the the tank had crushed coral instead of sand (which is ESSENTIAL for good shark husbandry).
While my shark was dying, I was making calls to a PhD shark specialist, who said that people who keep nurse sharks in home aquariums make him sick. They are just not meant to be kept in such small tanks, it's cruel. Please don't do it, you just encourage the trade even more.