My yellow still has remnants of those white lines on him after years, but they seem to be more pronounced on your fish. I would bet its just stress from going into a new tank. What are his tankmates and tank size? Do you have any fish that might be giving him any grief?
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18