Giving the fish an ID is already somewath troublesome.. The ones i bought were sold as Affinis with the given properties of the Vittatus, looking closer they also more look like Vittatus. Vittatus do not grow much bigger than 30 mm and Affinis next to the different color patern grows to 50 mm acording some databases.. Seems hard to keep them apart when in a younger stage of live.
There are some questions you could ask at the LFS to narrow it down a bit. AFAIK breeding oto in captivity is not easy and most offered are imported wild catch to keep up with the demand. So if the LFS is trustworthy and say it's captive breed it most likely will be Vittatus, they seem to be the easiest to keep and breed in captivity.. If it is wild catch you'll always be in for a surprice when it comes to give young fish a propper ID.
Also if they say it's imported wildcatch, ask how long they are in the shop.. If they say since last week, walk away and don't buy any. Oto's are very sensitive and stop eating due to stress, it's stated that most likely 90% doesn't survive the first weeks after capture and what's left a high percentage dies in the LFS or in home tanks the first weeks. So even if they are captive breed and there for probably stronger, still if they are fresh arrivals, don't buy them wait a few weeks and go back and buy only the active, eating and strong looking ones. Just to realese the stress a bit off them. Moving them arround a lot in short periodes aint very healthy for them..
Here you see how they are caught in the Oto factory.. 1 scoop 2000 oto's of which only 200 arrive at LFS of which a high percantage dies in home tanks.