To be honest, I would give them more time. it can take a couple days sometimes for the coral to adjust to it's new tank.
__________________ 180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40bREEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.
Duncans are hardy little things. Mine did OK...but then I found a sweet spot for them with my flow and they ahve gone nuts. Looking at your tank, there isn't anyway it will get the flow it needs there. It looks like it is in a dead spot. Move it to the other side so the PH's flow can let its tentacles sway in the water. Yes, it has only been 6 hours and it needs time to adjust to your tank. But where it is isn't going to help it out any.