They say to add all tangs at the same time. i did it within 1 week and still had issues. If it's been going on for a few days though, I'm not sure if they will get along eventually. :-(
It's rude since it was a gift, but can you exchange it for a different fish, maybe one you wanted and planned on getting?
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 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.