As a somewhat general rule (5 times out of ten, it works some of the time....), the larger fish would be more subject to dissolved oxygen or water quality issues.

I wonder out of 2 lbs of fathead minnows, what percentage does 70 dead minnows equate to?

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."