They are not fussy eaters and accepts a wide range of staple and live food.
Differentiating a A.viejita and a A.macmasteri tend to be an issue due to their close resemblance in colouration and dark marks. One known method of differentiating the two species is to keep a look out of the first rays of the dorsal fins, where A.viejita is known to show up with black markings while A.macmasteri doesn't. But then again, there are times from farm stock that the two species are mixed up and such traits are not accurate.
Another differentiating trait, albeit difficult to really compare, is the shape and size of the caudal spot. A.macmasteri has a caudal spot which is more elongated, covering nearly the whole of the caudal peduncle, while the A.viejita has a smaller caudal spot, and more rounded.