What is the term for a highly flavored stock made with fish bones?

The term for a highly flavored stock made specifically with fish bones is referred to as fumet. Fumet is characterized by its concentrated flavor profile, which is derived from simmering fish bones along with aromatic vegetables, herbs, and sometimes wine. This cooking technique draws out the essence of the fish, resulting in a stock that can enhance various dishes, particularly seafood-based recipes, due to its depth of flavor.

It's important to note that fumet is distinct from other stock types. For instance, glace is a thick, syrupy reduction of stock that is used to intensify flavors in sauces but is not made directly from fish bones. Bouillon generally refers to a broth, often made from meat, and doesn’t have the specific focus on fish bones like fumet. Remouillage, on the other hand, is a secondary stock made from the bones that have already been used in a first stock, serving a different purpose in cooking. Thus, fumet is specifically designed for imparting a rich fish flavor, making it the correct choice in this context.