After a week of being in my display tank, my Longfin fairy wrasse has yet to swim extensively in the open water. When I first added him, he was very lethargic and spent time either on top of my powerhead or in the sand. After the first day, he disappeared for two days and came out still looking very pale and stressed. While his color has improved significantly and he frequently emerges from his hiding spot during mealtime, he has yet to leave the sand bed for an extended period of time. Should I be concerned about his health, and is this a normal part of Fairy Wrasse acclimation?