Can any of the seafood in the spicy seafood pasta be substituted?

In a seafood pasta dish, the individual components, such as shrimp, mussels, and fish, are often carefully balanced for flavor and texture, as well as to provide the intended culinary experience. When the dish is specifically mentioned to be "already portioned out," it implies that the seafood ingredients have been pre-selected and measured to ensure the right proportions and balance in the final dish.

Substituting seafood components could disrupt this balance, potentially altering the dish's flavor profile and texture. Therefore, the idea that it is predetermined and portioned suggests that making substitutions would not be feasible or desirable. This is why the notion of being unable to substitute any seafood in the dish holds true, as it maintains the integrity of the recipe.