There are 2 sharks that can live, and be somewhat comfortable in a 150gal. tank. They are the Banded Cat Shark and Marbled Cat Shark. They grow to an average of 40"Very cute, and active as babies, but here are 2 things that the fish store doesnt tell you.
In captivity, 50% to 75% of them die within the first month by starving themselves to death. It's not the owners fault, it's just that naturally, they dont know to start eating. And IF they do eventually eat, it's already too late for them to survive. This happens frequently in the wild as well. They are just incredibly hard to get to eat. Frequently, even force feeding doesnt work (trust me, I've tried). I had my newly hatched Banded Cat Shark for 4 weeks before he died from starvation. My fish store actually told me that it would be hard to get him eating, but I thought..."ahhh, it cant be that hard. He'll eat when he gets hungry.".
The second thing is light. Most fish keepers have decent lighting (florescent) to superb lighting (metal halides, etc.). Sharks require VERY low light. Even florescent is too much for them, that's why they're mainly active at night. What's the fun in keeping a large fish tank that has to have extraordinarily low light?
Other than those 2 species, there are NO other sharks that you can keep in anything less that a 1000gal. to 10,000gal. tank. Alot of people get Horn Sharks...these grow to 6 feet. Blacktip Reef Sharks and Whitetip Reef Sharks, although absolutely gorgeous, can grow to 7+ feet.