  The one-loop induced Z --> g g gamma and Z-prime --> g g gamma decays are
studied within the context of the minimal 331 model, which predicts the
existence of new gauge bosons and three exotic quarks. It is found that the Z
--> g g gamma decay is insensitive to the presence of the exotic quarks, as it
is essentially governed by the first two families of known quarks. As to the
Z-prime --> g g gamma decay, it is found that the exotic quark contribution
dominates and that for a heavy Z-prime boson it leads to a Gamma(Z-prime --> g
g gamma) that is more than one order of magnitude larger than that associated
with Gamma(Z-prime --> g g g).
