Is it cycled? How long has it been since your cycle has started. If your tank is not fully cycled I am afraid you will keep losing fish.
If it is cycled though, I would recommend another clown to keep your other one company. The larger clown will become the female and you will see it assert its dominance overtime. They could possible even mate down the road.
You can look at Aquarium Fish: Tropical Freshwater Fish and Saltwater Fish for Home Aquariums
for fish. It will tell you weather the fish is able to be kept with coral, temperament, and the difficulty of keeping the fish. That way you have an idea of what direction you want your tank to go in.
Let us know what you decide on.