Only noticed it open late last night after a feeding (of the tank). In the 3 days I have had it originally opened almost fully for the first 6 hours, then I did a water change, and it went to about 50% I would say. I'm hoping it's just getting acclimated to the water and lights. Guess time will tell and obviously my water results tomorrow.How long has its mouth been opened? Even if its slightly retracted, it wouldn't be all bad but it really looks uncomfortable.
Did you use live rock for your tank?