Dwarf seahorses

I am starting up a dwarf seahorse tank and I have a fish in the tank. It is 5 gallons and it is ready for seahorses!!!! I know where to buy and what to feed. My question is coral and fish. I really want coral and fish. The tank is ready for everything. I went to the LPS and they said it was ready for anything. Even corsl!!!! I just need to buy...