The dish is popular in South America. The basic ingredient is raw fish, sliced into bite-size pieces and marinated in lime juice (orange juice, grapefruit juice and lemon juice all can be used), salt, and seasonings (usually chile peppers). The citric acid in the juice changes the texture of the fish, without changing its “raw” taste.
The citric acid in the lime juice does alter the structure of the proteins in the fish, making the fish more opaque and firm, just as if it had been cooked with heat. But the acid does not kill bacteria and parasites
Ceviche is usually made with sea bass or flounder, but just about any fish or shellfish will work. The other ingredients vary widely. Ecuadorian ceviche is often made with shrimp and ketchup in addition to the lime juice, and served with corn nuts. In Chile, ceviche is made with Chilean sea bass, grapefruit juice, and cilantro. In Peru, ceviche is garnished with thinly sliced onions and aji amarillo or rocoto chile peppers. It’s served with sweet potatoes and large kernel andean corn on the cob (choclo).