It does not seem to add any fishiness to the flavor profile. It is supposed to mimic dry aging, a process I don’t know much about. I like beef and have heard and read that aging is better because the bacteria breaks the meat down and makes it more tender. But that is what I got the APC for and why there are long cooking sessions.
I was very sparing in my application of fish sauce and I will try it again since I have a big bottle, but so far am kind of ‘meh’ about using it. It might be worth while to start a fish sauce topic and get some discussion about it.