Pictured for this week’s AquaNerd POTW is an orange-shoulder tang (Acanthurus olivaceus). This surgeonfish, as its name implies, has a bright orange streak starting behind its eye and going past its pectoral fin. As a juvenile, the orange-shoulder tang is actually a bright yellow, with a less prominent orange streak. As it matures, this tang loses the yellow and develops two distinct shades of gray. The first half of the fish is light gray, with the posterior a darker shade. The orange markings really stand out on the gray background, making this fish quite appealing to hobbyists.