  In a hydrodynamic model, we have studied $J/\psi$ suppression and elliptic
flow in Au+Au collisions at RHIC energy $\sqrt{s}$=200 GeV. At the initial
time, $J/\psi$'s are randomly distributed in the fluid. As the fluid evolve in
time, the free streaming $J/\psi$'s are dissolved if the local fluid
temperature exceeds a melting temperature $T_{J/\psi}$. Sequential melting of
charmonium states ($\chi_c$, $\psi\prime$ and $J/\psi$), with melting
temperatures $T_{\chi_c}=T_{\psi\prime} \approx 1.2T_c$, $T_{J/\psi}
\approx2T_c$ and feed-down fraction $F\approx 0.3$, is consistent with the
PHENIX data on $J/\psi$ suppression and near zero elliptic flow for $J/\psi$'s.
It is also shown that the model will require substantial regeneration of
charmoniums, if the charmonium states dissolve at temperature close to the
critical temperature, $T_{\chi_c}=T_{\psi\prime} \leq T_c$,
$T_{J/\psi}\approx1.2T_c$. The regenerated charmoniums will have positive
elliptic flow.
