Originally Posted by
Apistomaster
Your Angels do look like Altums to me but there is something about them that makes me think they are not the true altums from the Orinoco but rather the Alto Rio Negro P. scalare which resemble altums. The relative hight of their dorsal and anal fins is a little short for their body size. True Orinoco P. altum have a higher fin to body aspect ratio than the so-called Rio Negro Altums which are officially recognized as P. scalare. By definition, P. altum are solely from the tributaries of the Orinoco. (they don't actually live in the Orinoco proper.)
The fish derived from Linke's strain are widely considered to be actually Rio Negro "Altums" and they are typically large bodied but shorter finned fish as well.
Other than these differences between body size to fin hight, these angels have altum-like stripes, body shape and are generally larger than a "standard' wild P. scalare. They are also an easier fish to keep than true P. altum.
Real P. altum often grow to nearly 18 inches tall in an aquarium as measured from tip of dorsal to tip of anal fins. They get even taller in the wild. The Rio Negro "altums" never grow that tall.