I'm kind of hung up on the "huge amounts" of water if using fish. That kind of contradicts the digestibility of fish which is the most easily assimilated protein of all meats, even oily fish.
As far as dog kibble I tend to agree it runs on the "dry" side, maybe the processing as fish is a more delicate meat source? Anyhow it sounds backwards to me that fish would burn hotter in a dogs gut as it is digested with much less energy than other meats.
I tend to look at nature (don't laugh ) for simple answers to these types of questions, as the scientific answers are over thought and complicated imo.
What mammals feed on fish? Big brute types like Bears
What mammals feed on birds? Small scavengers
What mammals feed on red meat? The apex predators Lions and Tigers Oh My!
I like to incorporate all meat sources, I let the individual tell me which they work best on. What I've found for myself is the endurance runners tend to do best with more chicken while the true power houses need more red meat to support their strength.
I'm always open and continue to learn, this topic I very much enjoy.
S_B