I made it to the top of the skull tower. Yeah, the flails are the thing to use against the fish. Yes, they will get through your defenses when your combo ends, and you will take a hit or two and won't be able to prevent it, but the ones you've already killed have probably left behind enough life refills that it won't matter -- assuming they don't get such a good grip that they kill you instantly. But I guess even that's unlikely (though they did take off 1/3 of my life once -- which was still later refilled) since you've cleared out so many that there'll only be a couple left to attack at first (the amount of damage you take is a cumulative function of how many fish latch on). I still don't know if that would work very well in an area with "infinite" fish, but it works there.

I didn't even have too much trouble with the dragon fiends. I practiced a little against them in the place where you fought Doku (not enough to win the "challenge", however). Normally, your combo with the big sword ends after six hits. That's not enough to kill them, but if you can get it swinging again, about 9 hits will kill them. One thing that works sometimes is blocking; they'll attack you twice, then you can counter. But that's not a fantastic strategy because they can simply throw you, which negates your block.

"Perhaps one did not want to be loved so much as to be understood."
-Orwell