An 87-slide presentation in which I thoroughly analyze and answer the question: "Is cooking fish worth the time?"
Started as some napkin math a few weeks ago and spiraled out of control. After day two it just became a personal project I wanted to see through. I thought you all might find some amusement in this ridiculous over-analysis though.
TL;DR:
At best (and when I say at best, I mean it), cooking your fish provides about 1,500 more gold/reputation per hour than cooking no fish at all, at the cost of catching 8 to 10 less fish per hour. That's the value of one mermaid/siren gem (before any emissary bonuses) per hour.
So, if that ~1,500 gold is a big deal for you, then by all means, cook up some fish. I have found the perfect combination of exactly which fish to cook so you don't have to. Otherwise, don't bother.