Which level of fishing is best for farming proofs?
I now have lvl 22 and I get only keys and fish scales which I don't need

Level doesn't matter. What matters is the fishing expertise as far as I remember back when I was fishing on retail.

Now the point is that after some expertise you'll get alot of recipes and key mats, but it doesn't affect your pocaf gain too much afaik, so max it out. The total cost of fishing skills (including expertise) is under 4kk adena. But you can craft alot of good stuff from that. For me on retail it was worth the investment.

Sadly, fishing is irrelevant on most privates because the fishing reward doesn't go up with the rates. On retail it's a pretty profitable business. I used it on dex 4x too. Not so much success, but still better than nothing. So on something higher than let's say 5x it's pretty low. Sure with the new chronicles there are many more ways of making money. I used fishing back in c3(or c4?)-interlude.

Yeah I meant fishing expertise...

And do you have any short cool guide how to profit with fishing? I really like it and it would be nice to make it even more useful

My current server is 6x OFF gracia final and it's well populated (about 1000+ uniques), but so far I haven't seen many people buying proofs, and when so, only for 1,5k per piece or something .(

Get max lvl on that shiat and use prize winning lures. With those u will only get chests with imba prizes inside!

And any quest needed to catch those prize chests? And isn't that just some event?

1.5k per pocaf isn't such a bad price. You get thousands of those pretty quick at high level.

It's not spread because it's a 6x. If it was a 1x believe me, it would have been a market segment just on pocaf.

No event whatsoever lol. Go to the shop and buy prize-winning fishing lure.

Yeah I'm using them since always but no chests so far