90 gallon seahorse tank?

How many of these can I put in a 90 gallon tank? http://ift.tt/1sI7ghG



How about these? http://ift.tt/1u9xuMS



And a completely out there question I would totally never do, what about dwarfs? How many of those could you put? I wouldn't do it. I'm thinking about a 2.5 dwarf tank.