I agree with a few things mentioned here. First, 300 gallons would be a good sized tank for a cat shark. I also agree that keeping sharks is cruel to some degree. Keeping pelagic sharks or larger species like nurse or black tip sharks is best left to public aquariums. Bamboo and cat sharks are benthic and not as active as other shark species. However, I would not raise the shark from an egg. The young shark could be delicate.
Rule number one: Always research a fish before you buy it.
Rule number two: Always cycle your tank.