Thought I'd chime in, that is if you are still paying attention to this thread. If I have not misread, there were no dimmensions given as to the size of display this animal will be housed in nor future housing size? Depending on the depth, metal halides could be used, but taking care as to not overlight and cause radiation suntan. If you plan to house soft corals in this tank then metal halides are not needed and PC
's or T5's can be used. Be aware that although this animal will not consume corals, it may trample over and around them causing tissue recession from non-expansion or possible damage. Majority of crustaceans and polychaetes will also be consumed with the possibility of slow moving fish. Actual display size may vary depending on specie, which I believe you also did not relay, but on average a 500g display would be adequate for long-term care/adulthood. Being that this animal has been kept for at least 1yr (juvenile) and is only about 6" might be a concern in comparison to averages.