  In this article, we introduce a differentiability concept for fuzzy functions
$\tilde{f}: F(\mathbb{R}) \to F(\mathbb{R})$, where $F(\mathbb{R})$ is the set
of all fuzzy numbers. With the help of the proposed differentiability notion,
we prove a necessary and sufficient condition for optimality to obtain a
non-dominated solution of a fuzzy optimization problem.
