When I'm just cooking for family dinner (4 people), I'll cook up around 20 fillets, that gives us some leftovers for the next day. For the neighborhood fish-fry I do a couple times each summer, I do like a couple others and figure on 5 or 6 per person, along with salt-potatoes, coleslaw, and whatever sides the neighbors bring. There is usually fish left over, and we send some fillets home with everyone and have a few leftover fillets for ourselves. Works out good for everyone to eat their fill and have a fish sandwich later on.