I've been big fishing since 2.2 and I love FSH but EW big fishing has been disappointing to me. This disappointment hits hard because changes to the kit in 6.0 give FSH such a robust skillset now, but when it comes to EW big fishing we got one fish that lets the current kit really shine and show what I like most about the job and that's Durdina Fish.
Fishing for it efficiently involves using at least: Identical Cast, Patience II, the Hooksets, Chum, Surface Slap, Thaliak's Favor, Makeshift Bait.
There is potential to use Prize Catch and Patience as well.
Why I think this fish really lets the kit shine is not just because of the quantity abilities used relative to most EW fish, but how they get used. Fishing efficiently for Durdina Fish does not involve rote/static ability or GP use, it requires reactive decision making based on what happens.
There's a general "opener," if you will, of: prep AA stacks, IC a Sardine, start with Patience II and Hi-Cordial, but after that what to do is based on circumstance.
Whether your first heavy investment of stacks goes to MSB or TF varies. How much or often you can maintain Slap and Chum is based on what bites and how good you are at GP management. You know you will be building further AA stacks and can act now with the expectation of the GP you will be regaining from the stacks later.
Why I think even this simple distinction is important is that Durdina Fish creates friction, but the good kind, in my opinion.
With our effective GP pool it seems it's difficult at this point to really create a strain on our GP, and I personally find GP constraints enjoyable. I love this type of friction. I love when FSH requires reactive decision making as this is when the job most rewards your knowledge of it.
Admittedly we've never had a tonne of fish like this, and I also think this is fine. The older fish that maintained friction similar to this don't anymore as a result of the EW kit unless you make it yourself with something like fishing for Warden with Fish Eyes, which I would have been fine with if we got new fish that did. We're set up for it after all.
Snowy Parexus and Mayaman are the other EW fish that do this best, in my opinion, but it's a different kind of "engaing" to my mind. Gharlichthys and, to a lesser extent, Sidereal Whale do as well or at least could. For Gharlichthys you can circumvent the strain entirely, and Horizon Event not being a potential Mooch loop and being higher bite rate and shorter bite time than Shadowdart Sardine makes Whale feel less novel than Durdina does to me. If you had to catch the EBEs and Unbegottens during the Whale window, maybe, but since you can prep them in advance a lot of the strain during the Whale window itself is gone.
I don't think that all big fish should be like Durdina Fish, or even most. But I think it's really clever and fun and would really love to see more than one fish that creates this type of "constraint" or "friction" in the future.