Symmetric and skew-symmetric matrices

In $\begin{bmatrix} 2 & 5 & 1 \\ -5 & 4 & 6 \\ -1 & -6 & 3 \end{bmatrix}$ every entry off the diagonal is the negative of its mirror image: $5$ and $-5$, $1$ and $-1$, $6$ and $-6$. Is the matrix skew-symmetric?