  We consider general 5d $SU(N)$ quiver gauge theories whose nodes form an ADE
Dynkin diagram of type $G$. Each node has $SU(N_i)$ gauge group of general
rank, Chern-Simons level $\kappa_i$ and additional $w_i$ fundamentals. When the
total flavor number at each node is less than or equal to $2N_i-2|\kappa_i|$,
we give general rules under which the symmetries associated to instanton
currents are enhanced to $G \times G$ or a subgroup of it in the UV 5d
superconformal theory. When the total flavor number violates that condition at
some of the nodes, further enhancement of flavor symmetries occurs. In
particular we find a large class of gauge theories interpreted as $S^1$
compactification of 6d superconformal theories which are waiting for
string/F-theory realization. We also consider hypermultiplets in
(anti-)symmetric representation.
