How does fishing mechanics work these days?

[MagicManICT]

I have no idea.

What? Not even a hint?

[Sevenless]

I have never been a good fisher, though even in w4 I got more fish of different types than now without deepening into the details.

Is the wiki up-to-date on the subject? Are there any other factors (apart from moon, time of day and type of water) which define what type of fish do you get? Is there a factor of luck/randomness?

Definitely isn't luck. If you fish with a certain set of equipment you will always get 1 or 2 types of fish consistently during that time/at that location. Quality of everything only softcaps, but I've heard a lot of people claim better Q lures speed up lure fishing. Can't personally verify that yet though. I should probably test that XD