Clownfish do not need anemones at all. I don't understand Laddy's metaphor there, but I agree with what he was saying.
Also, if you do not have metal halide lighting, I would not plan to get an anemone. They will not live very long in your tank without VERY strong lighting. They are a delicate animal and need experienced care. They also require an established aquarium.
Clownfish are a hosting fish, so more than likely, they will host just about anything. Heck, I have one that hosts a rock.
The only thing I would recommend is to get more live rock in that tank. Your tank will be a lot healthier, and the water parameters will be MUCH more stable.