"That is, every 0.7 pounds of high-protien/high-fat sinking pellets produced 1 pound of flesh..."

You got more weight put on the fish than you fed it, Ken?

If correct, does this mean there was other forage the fish were eating, or am I missing something?

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."