  We construct a ring of meromorphic Siegel modular forms of degree 2 and level
5, with singularities supported on an arrangement of Humbert surfaces, which is
generated by four singular theta lifts of weights 1, 1, 2, 2 and their
Jacobian. We use this to prove that the ring of holomorphic Siegel modular
forms of degree 2 and level $\Gamma_0(5)$ is minimally generated by eighteen
modular forms of weights 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 10, 11, 11, 11, 13, 13,
13, 15.
