Along with getting better lighting (T5's or MH or both), I would recommend getting a bigger tank. A 12.5 is too small for ANY of the clown hosting anemones. You could keep rock anemones (E. crucifer) but your tank is, in general, too small. If you did get a small one, you could keep it in the tank temporary but the nem would need to be given a bigger tank, not only for space, but also for stability of water parameters.