They are generally considered non-reef safe due to their eating habits, but if you dont have any inverts, or dont mind them being eaten, thats no problem. I do agree though, a 14g is too small for a Flame Hawk. Id suggest a 30g tank. They arnt open water swimmers, more perchers, but they are active. I hope he is moving though, how long after acclimation was that pic taken? He is slightly off colour, and sitting on the floor, which is a bit concerning.