You must be doing something wrong and just confusing others with false info. Here is one of the recent posts from the player who is involved into fishing. As you see, you can get more profit in shorter terms than you say. And when we looked into our statistics, we could confirm that such results (and even better) are reached not only by this player but by many other skilled fishers as well.fishing is one of the worst things u can do i did some tests while ago and to spend 12k labor (daily labor income) u need more less 15-17h and ur profit will be around 3k what will give something like 200g per hour.
Depending how many gargs you fish and what type, you can still get sort of close to 250-300g per boat.
I know it seems disappointing at first glance, but really, it is super nice to have consistent fishing now and then earn a little bit less on the marlins, rather than search for spots for ages, wait on a bite for ages, lose lures in the process, and then maybe fill 3 or 4 boats in the 2h of the mermaid buff/active fishing rod. Now I easily filled 5 boats with time to spare.