Gem tangs are getting pretty common now. I see them all over the place online for sale. The price seems to have come down a lot over the years. Some people have also reported buying them at Petco. Andy, how big is your qt tank? 5 months sounds like a long time in a tiny qt.
I have gem tangs collected 6 yrs ago to recently and the one coming in now definitely has more lines. Getting gems with dots now can be tricky and same with black tangs because they been crossbreeding like rabbits