IMO you should not get a shark unless of course you already have it's future home. Sharks get very large and will outgrow your 150 in no time.....
Please don't get the shark egg!!!!!
There are sharks available that will live out their life in a 150 gallon tank assuming it is 5' long and about 2.5' wide. Without knowing what type of shark it is this statement has no merit. A couple of commonly available sharks that would do fine in a 150 are coral catsharks (
Atelomycterus marmoratus) and the Marbled catshark (
Atelomycterus macleayi).
Another thing to consider is dimensions not gallons alone. A 5' long tank that is 2.5' - 3' wide would be fine for one of the previously mentioned sharks. Also, these catsharks need hiding places so an appropriate amount of rock is necessary. Coral and Marbled Catsharks are sleek bodied and extremely agile. Naturally they live within the reef searching for inverts and small fish in crevices. They also spend most of the day hidden and become active at night.
Putting a new born shark in even a 150 gallon tank is a bad idea. They are roughly 6" when born and stubborn feeders. Considering their instincts to hide and the need to be constantly offered food the first few days to a week becomes more challenging in such a large tank. They most likely will starve to death.
Tangs Rule, as others have mentioned, I wouldn't risk the shark egg in a tank treated with copper. Various fish have different tolerance levels of copper and I can tell you that a developing shark embryo is very sensitive to copper and other water parameters changes/pollutants while still in the egg.
Do you know what kind of shark egg you want to buy? If it is what is commonly available my guess is it would be a Brown Banded Bamboo (
Chiloscyllium punctatum) which will eventually need a tank that is at least 8' long and 3' wide. It would take 2-3 years to be full grown but you will not find a market for that shark once it reaches that size. People are trying to get rid of them all over the place because they bought them as eggs and did not realize how big they actually get (about 3' long but also about 6" wide and active). If you really wanted a shark I'd replace the tank and go with a Coral or Marbled Catshark. They also lay eggs but you probably won't be able to find any for sale. The good news is you can find them pretty small at reasonable prices.