Are bright yellow Betta fish with opaque fins rare(vietAil)?

yellow bettas are not common that is for sure ... good for you for grabbing him as he sounds beautiful ... i always tell people to go when stores get their shipments as almost every shipment will have one or two unique fish even petsmart :O) you should post a picture :O) you might want to reconsider feeding freeze-dried as the fish can sometimes gulp the hard worm and it can cause a blockage ... you would be best to feed the betta pellets and the frozen blood worms ... i would watch his rubbing on stuff, it could just be adjusting to a new tank ...