Here's a link to many different preparations:
I've been enjoying Japanese preparations (most undergo some degree of aging) for most of my life, but recently I have become addicted to Italian crudos - the combination of good quality fish drizzled in good olive oil and salt seems a refreshing (change) and IMO better way of tasting at least some of the fish. I generally understood that fish served as crudo are not aged (correct me if I am wrong) but I was surprised to encounter aged mackerel in one of known crudo/Italian place in Manhattan, and while un-aged fresh mackerel I find very nice, aging does bring out best of its flavors for mackerel IMM, and wonder if this is a common/traditional practice in Italy for some of the fish that taste better when undergone a degree of aging? From online search, I do encounter mediterranean chefs aging fish before grilling, and personally I sometimes enjoy lightly salted and aged (usually 1-2 days) fish for grilling.
I very much enjoy ceviche, especially Peruvian versions. For a long time, I preferred quick marinade of less than a minute which is a modernized version, but my recent trip into the Peruvian Andes I had mackerel ceviche at a market that was marinated well beyond 24 hrs which is a common practice there and was served along with a bowl of warm broth made of of mackerel parts (variant from the coastal leche de tigre which is just cold ceviche marinade liquid served alongside). Quite delicious though not something I could eat daily.
As a Korean, I enjoy hoe as well which is un-aged fresh fish most often prepared after you pick a live one out of a tank in a restaurant or from the boat returning from a morning catch; these are usually white fish enjoyed for firm/chewy texture it retains at fresh stage (one of the better example of this is cuttlefish or squid - when sliced into slivers alive, they are crunchy and firm and not mushy and soft which is often the state at the markets). Dipped in gochujang/vinegar sauce the actual taste of the fish gets lost a quite a bit, but while trends are changing, my culture has embraced this for a very long time over the Japanese process of aging. As the process of killing the fish is different, hoe require a tank in the restaurant/stores before getting sliced and plated vs sashimi which is already killed at the market and stored at home or restaurants before being sliced and plated (again, those with more insight into this please correct me if I am off).