There is no way to make a definite ID that this tarantula is Aphonopelma anax based on this picture alone. It looks large and bulky like A. anax, but it looks like a few other American Aphonopelma species too. Did you collect it yourself from south Texas or buy it from someone?
@TrapdoorSpiderLover Then there is no way to reliably ID this tarantula as A. anax from a picture. If you managed to get a good, clear picture of the palpal bulb then it would be possible to ID it since A. anax has a distinct shape of the embolus compared to all other American Aphonopelma species. Unless you're planning on breeding it (which I would highly suggest you don't) then it doesn't matter what you call it.