Induced activation of the gamma-aminobutyric acidA (GABAA) receptor in the retina of goldfish caused the fish to rotate in the opposite direction to that of the spinning pattern during an optomotor response (OMR) measurement. Muscimol, a GABAA receptor agonist, modified OMR in a concentration- dependent manner. The GABAB receptor agonist baclofen and GABAC receptor agonist CACA did not affect OMR. The observed modifications in OMR included decreased anterograde rotation (0.01∼0.03</SUB>ՌM), coexistence of retrograde rotation and decreased anterograde rotation (0.1∼30ՌM) and only retrograde rotation (100ՌM∼1 mM). In contrast, the GABAA receptor antagonist bicuculline blocked muscimol- induced retrograde rotation. Based on these results, we inferred that the coding inducing retrograde movement of the goldfish retina is essentially associated with the GABAA receptor-related visual pathway. Furthermore, from our novel approach using observations of goldfish behavior the induced discrete snapshot duration was approximately 573 ms when the fish were under the influence of muscimol.