Was in a pet store earlier and they had a tank with these gorgeous fish in, unfortunately they weren't labelled and the staff were useless.
They were only little (obviously I've no idea if they were babies) about the size of neon tetras. They had a black body with white spots (think polka dot pattern) and they had red dorsal fins which as far as I can remember ran most of the length of their body. I believe they also had a red tail.
Sounds like a celestial pearl danio. Lovely little fish, they are fairly new to the hobby. They are pretty easy to care for and awesome to watch. The males do this amazing dance to establish dominance.
I would think twice about buying from a shop where the staff don't know what they're selling though! I've seen shops selling fish that can easily grow to 3+ feet and there were no warnings anywhere.