A curve has equation $\frac{x^{2}}{1+x^{2}}+\frac{y^{2}}{1+y^{2}}=x^{3} y^{5}$. Find the equation of the tangent to the curve at the point $(1,1)$. Give your answer in the form $a x+b y=c$, where $a, b$ and $c$ are integers.

[6]