take 1 fish from 1st crate, 2 fish from 2nd crate, 3 fish from 3rd crate, etc. until you have fish from all of the crates, then weigh the new crate and however many ounces you are over is the crate that holds the oversized fish!
However now you will have to sort out the crate you just weighed, maybe one at a time!
However now you will have to sort out the crate you just weighed, maybe one at a time!