Well, if my semantics aren't mocking me, burning fish should return coal instead of a cooked fish.

Lol, so using fish as fuel in the campfire should return charred fish? Or just cooking them on the campfire would return it?
I’d need to make some new sprites but I do love that it would be funny

Interpreting your questions as answers sounds interesting :D

Actually i meant, it's weird that furnaces, which are designed to smelt metal are able to cook fish at high temperature, simply from the perspective of a cook i mean.

Oh haha I misread your original message- thought it said charred fish instead of coal.
But yeah, you have to suspend disbelief a bit. I guess we can consider the furnaces to be “smart” enough to smelt at the correct temperature for whatever is in them. I suppose copper and iron have different temperatures they need to be smelted at, although those are much closer to eachother than fish would b to either… hmmm

Maybe I can adjust the recipe to be very fast, so the fish is only cooking for a short amount of time

How about you combine both ideas: the recipe returns very fast a charred fish.
What do you think?