I love good discussion with real facts and citations. Lets me play with numbers!
So let's look at this another way that I think meshes with the additional input above. Those 2000 CNBG weigh 680 lbs now. Where did it come from? We use 760 lbs of feed and a 2:1 conversion. That accounts for 380 lbs of fish. That leaves 300 lbs from "other" and if it's less efficient, let's go back to 4:1 until we see otherwise, that means another 1200 of self-foraged / not fed intake.
Now we paid for 56% of the weight added to the fish, while it is 38% of the weight consumed. That sounds more in line with Ewest's quotes.
If we pursue Bill's hint that conversion might be better, let's arbitrarily consider 1.7:1. In that case, you get 66% of the fish weight from pellets, and pellets are 45% of weight eaten.
when we assume pellets and other both convert at 4:1, they had to eat 2720 lbs. But at 1.7:1 pellet and 4:1 other, they only had to eat 1692 lbs. That's a lot less chomping, beside the fact that pellets are usually regular, dense and don't swim away.
