Carrie is correct, seahorses and jellyfish especially are out of the question for your clowns. As for anemones and your lighting question, you will need around 4-5 watts/gal to carry most anemones. Water quality should be your main concern, however, as anemones are very delicate creatures. If you are not rather eperienced in reef-keeping, you may want to wait a while on an anemone and go with some mushrooms and such first.