Nope, no real sharks that will fit into even large home aquaria very well. There are a few that exist, but they are not available for sale, some are endangered species, and survival rates are terrible, even for commercial aquariums.
Shark-like--what do you mean? Shape? Color? Behavior? A 30 will really limit you, as most predators get too big. There are 2 types of predators: lurkers, like lions, that spend most of the time in hiding, waiting to gulp down food in a burst of movement; hunters, like eels and sharks, that actively search out food. Lurkers typically can be kept with fish that are too big to eat, while hunters will often harrass and kill fish much larger than themselves, limiting appropriate tankmates even further.