Ceviche (an alternate spelling) can be eaten as an entrée as well. In this case, this will be enough for about two people.
More traditional recipes call for much less marinating. In fact, some will marinate it for as little as 10 minutes total (basically just the time it takes to get the sides ready). If marinating for a small amount of time be aware that the acidity of the lime is the only thing that "cooks" the fish.