Yes and yes, I have and did both.Give him a bit to settle in, and try letting dried foods soak in a bit of tank water before adding them. If the tank cycled? Do you have a test kit to monitor ammonia levels? Did you treat the water for chorine/chloramines?
It's at 79.2.What temp is the tank? I agree that he'll likely be fine so long as water conditions are good, but if the temp is lower, that's also going to reduce his hunger. If he still is't eating after several days, see if you can get some live food to offer.
Keep in mind that fish can go for quite a long time without eating just fine.
The one with algae stains is from another tank.Curious...are all the plants artificial? Seems odd on such a new tank to have algae stains on some unless borrowed from another tank.