I didn’t buy than as anything in particular, got them from a local breeder as I liked the look of them didn’t ask at the time but was just inquisitiveMaybe an altum x scalare.
What did you buy them as?
There are altums from a lot of areas and most of them vary a bit so they could be pure altums. Normally if you are getting wild caught fish or fish that are only a few generations captive bred, they come with a river name (eg: Pterophyllum altum Rio Oronoco).