  We systematically study hidden-charm pentaquark currents with the quark
configurations $[\bar c u][u d c]$, $[\bar c d][u u c]$, and $[\bar c c][u u
d]$. Some of their relations are derived using the Fierz rearrangement of the
Dirac and color indices, and the obtained results are used to study strong
decay properties of $P_c$ states as $\bar D^{(*)} \Sigma_c$ hadronic molecules.
We calculate their relative branching ratios for the $J/\psi p$, $\eta_c p$,
$\chi_{c0} p$, $\chi_{c1} p$, $\bar D^{(*)0} \Lambda_c^+$, $\bar D^{0}
\Sigma_c^{+}$, and $\bar D^{-} \Sigma_c^{++}$ decay channels. We propose to
search for the $P_c(4312)$ in the $\eta_c p$ channel and the
$P_c(4440)/P_c(4457)$ in the $\bar D^{0} \Lambda_c^+$ channel.
