Seafood is kind of bad in the capitol but good otherwise.
It's mostly true in the capital. Seafood starts are slower to get started as you need to always rebuild a workboat.
That and the yield from every other special is generally better. Clams and Crabs are 4-yield which is like non-irrigated rice...
Early on seafood is susceptible to barbarians, later on to AI naval superiority. Oh god the naval superiority of a deity Shaka.
I just had a 1 rice 2 floodplain start on fractal, I didn't think you could only get one resource if you SIP Checked worldbuilder and sure enough, one non irrigated rice as the only resource in the BFC.
I'd take seafood over that any day