Because opercular abduction associated with agonistic display in the Siamese fighting fish is a highly stereotyped,well described and easy to elicit behaviour [11,18,20], it is particularly useful for testing the present protocol. Opercular abduction is mediated by a single muscle, the dilator operculi [5,13]. This is a superficial muscle that is easy to identify. In spite of its relatively small size, the activity of this muscle was not affected by the implanted EMG
electrode. We have detected no qualitative or quantitative differences in the kinematics of the display behaviour between normal fish and fish subjected to the present protocol.