Yea my LFS got some blueberry tetras and one of the first things he said was they are going to lose their color cause it's just dye... I was like What? That's just not cool... I was sad cause I really liked the color.
I assume it may also depend on the size of your tank. I think anything smaller than 15-20 gallons, keeping Bettas with a whole school of Tetras may be troublesome. But I don't personally have Tetras, so I'm not definite on that. Just something to think about.