Shame on the LFS that sold it to you, the first question they should ask is if you have an 8' tank for this fish. A 1 1/2" vlamingi will grow to well over 6" in the first 6-8 months, then slow down considerably until they reach adulthood. I do see a few 12" vlamingis here and there but not too many bigger than that, and even though they are listed as attaining 24" that may be a stretch, or at the least a very old fish.
It is unfortunate that they are collected so often, hardly no one has the means to care for them after they're a few years old. It's just so hard to pass up those cute silver fish with blue dots, and the LFS wants your $59 so badly they'll tell you what you want to hear. "Oh yeah just trade him back in when he gets too big", problem is the LFS doesn't want them when they get big either.