Nori that is clean and has been sorted to exclude sealife does not taste like fish at all. If it tastes like fish, it’s because it contains fish. The only way to avoid it is to go by 1) reputation and 2) taste. My experience is to go by taste because even the so-called vegetarian brands often contain sealife in the nori. You can taste it.
Hmmm… the question is – even if nori is “sorted to exclude sealife” – is it VEGAN (my definition/motivation of vegan is ethics, health is just a “nice side effect”)? I mean, ok, maybe they remove the fish stuff, but the fish died for producing it, right? Is there a “method” (or company offering such a product) of getting nori without catching the poor fishies? I didn’t really, seriously care too much about nori not being raw, but THIS would definitely put me off.