Any food fish are eager to eat is good food.
That would be incorrect, just as incorrect as it would be for one to place a large emphasis on simply maximizing the growth in their fish. It's actually very easy to net large gains in growth in a fish, and at a fraction of the cost of foods such as Massivore. If anyone doesn't believe that take a trip to a local commercial Sturgeon farm, where mature females can weigh in excess of 200 pounds, and 10+ ft in length. Take a look at some of the Beluga Sturgeon in the following vid, which I can assure you were not raised on Hikari Massivore.
http://www.sturgeonaquafarms.com/
With caviar from sturgeon selling from $500-$5,000+ per pound (depending on the species), these commercial farmers take growing out "monster" fish fairly seriously.
Ditto to the large commercial salmon & trout farms, where feed costs can equate to hundreds of thousands of dollars per year. The main goal of these farms is to grow fish out as fast as humanly possible, and as cheaply as humanly possible. Unlike a sturgeon farmer they are not so much concerned about the growth & longevity over several years, but to get their fish as large as possible as quickly as possible so that they can get those fish to market. You want to see large net gains in growth, spend a day talking to those fish farmers & you'll learn a thing or two about maximizing growth. And again, they aren't feeding Massivore.
Even with the largest of carnivorous predators raised in captivity, once the fish get past the fry/juvenile growth stage of life, the crude protein levels in their feed typically drop to 40-45%, it is the crude fat content that stays relatively high, at approx 14-20%. This is what really enables massive gains in growth, as the high fat content ensures that zero protein is going towards supplying energy.
The problem is that most warmwater tropical fish will eagerly consume food that is excessively high in protein and/or fat, because through the evolution of survival instincts they are hard wired to do just that. Most fish also find this type of food more palatable, just as most kids will choose a cheeseburger & fries, over a fresh seafood salad. But that kind of growth, and diet, long term does not always equate to healthy growth in warmwater ornamental species of fish.
There is plenty of monster fish food out there, and most of it costs a fraction of what some hobbyists are paying to feed their *monster* fish.