not feeding

Good afternoon! I have a 6” magnificent Foxface that I ordered online that I’ve had for 2 weeks now. Still a little shy, but has been getting much more bold in the tank. The problem I’m having is with feeding it- the fish is only grazing in algae in the tank. I feed LRS reef frenzy and mysis...

My yellow tann just stopped eating...No visible signs on it's body...no labored breathing...no erratic movements...just will not eat. It has been almost two weeks it has been behaving this way...just swims around the tank. I have been feeding Nori and a mix of frozen foods. All of the other fish...