  We show that a subdominant component of dissipative dark matter resembling
the Standard Model can form many intermediate-mass black hole seeds during the
first structure formation epoch. We also observe that, in the presence of this
matter sector, the black holes will grow at a much faster rate with respect to
the ordinary case. These facts can explain the observed abundance of
supermassive black holes feeding high-redshift quasars. The scenario will have
interesting observational consequences for dark substructures and gravitational
wave production.
