Ceviche and marinated fish...

Ceviche is wonderful

The origins of the dish are disputed, but it likely originated in multiple places in the world but became widespread during the Spanish colonial period. It is very popular in the Caribbean, Central and South America, the Pacific Islands (it is referred to as Kelaguen in the Mariana Islands, such as Guam and Poke in Hawaii), Southeast Asia, Spain, and Sicily .  Basically it is "cooking" raw fish or other meats by marinating it in citrus juice or other acids.  Lemon or lime juice are the most popular for making Ceviche.  Similar dishes were done using vinegar. You absolutely want to use high quality fish or mollusks when making ceviche.

Ceviche is also seasoned with chopped hot peppers, onion, fruit, avocado, cilantro, and other herbs.  Grated coconut is added sometimes.  The general rule of less is more applies.  This is a dish best done with a limited number of contrasting flavors.

White fish such as snapper, wahoo, mahi, toothfish, monkfish, and halibut are generally preferred for aesthetic purposes of the fish turning bright white by the citric acid, it is often done with octopus, shrimp, squid, or other fish.

Chicken is sometimes used, especially in Guam, but it is cooked in advance.

Swordfish, cod, and eel are generally not good for ceviche.  If a sushi bar does not serve it raw, you should not serve it raw.  Most sushi fish is frozen first, usually in a box freezer, to kill any parasites.  Lemon and lime juice alone will not get rid of parasites.