Determine for which values of $(a, b, c, d, e, f, g, h)$ is the following vector field Hamiltonian

Question

The vector field is given as:

$x' = −\mu y + ax^3 + bx^2y+cxy^2+dy^3$

$y' = \mu x + ex^3 + fx^2y + gxy^2 + hy^3$

So what steps do I need to take. Do I need to compute the Hamiltonian function first?