High protein high fat promotes growth in fish. 47% and 5% are minimum, not typical analysis. I once read the typical analysis of crude fat for massivore was close to 10%. So safe to assume typical analysis would be more along the lines of 50% protein/10% fat. Pretty nutrient dense for any adult fish, let alone those that spend most of their day laying around.
Increased palatability (taste/texture) equates to increased consumption. IMO far too many obese fish in this hobby, feed sparingly if choosing this diet, or one similar, for fish that aren't on the move 24/7.