I think it's probably a safe bet that that is NOT how they will end up looking. I wouldn't count on them getting brighter, but I would almost certainly bet that under a different intensity lighting the pattern, intensity, and possibly, only possibly, the coloration will change. I haven't met a zoanthid yet, and I have more than 20 kinds, that hasn't changed under changes in lighting. Some look completely different in the top and bottom of the same tank.