So I dried some of the new weighted fish, and they all seem to have the same values, regardless of weight, and a low value at that. Something like 8 humors when eaten, 1.0 - 0.0 glut values, and when I tried eating them it was around that, give or take. Not exactly 1, but like, 1.7 or so.
So it's not scaling, at least. They all seem to be about the same as far as I can tell.