Normalize the cubic anomaly coefficient of the fundamental to . The two-index antisymmetric representation has anomaly coefficient , while an antifundamental contributes . Cancellation of the gauge anomaly requires
The electric quarks give copies of the fundamental, so
In the magnetic theory the color components of transform as flavor antifundamentals and contribute . The singlet is the two-index antisymmetric representation of , whose cubic anomaly coefficient is . Hence
This is a direct anomaly check of Seiberg duality.
Choose the flavor orientation in which each electric is a fundamental of . Its color components then give
In the magnetic theory, the eight Spin(8) components of transform in the antifundamental and contribute . The singlet transforms in the symmetric representation of , whose cubic anomaly coefficient is , while and are flavor singlets. Therefore
where was used. The two 't Hooft anomalies match, as required by Seiberg duality.