Fig. 6. Magnitude of kinematic variables for body and fins during steady swimming. Green bars represent the left fin and red bars represent the right fin. Body and fins moved symmetrically around the midline of the fish [excursion to the left (cm)=excursion to the right (cm), P>0.07]. Fin excursions (body motion subtracted) were larger than body excursions (P=0.0011). For all remaining variables, maximum values were significantly larger than minimum values for each fin (P<0.0001). Right and left fins did not differ in fin area, fin or body velocity (black bars), or fin angle with the transverse plane (P>0.05). Left and right fins did differ in angle with the sagittal plane; right fins had larger pronation angles than left fins (P=0.0001). Large angles (rad) represent fin adduction/supination and small angles represent fin abduction/pronation. Asterisks above the bars denote significantly different values within fins (P<0.0001). Asterisks below the bars denote significantly different values between fins (P<0.001). Fin excursion, fin area and fin angle with the sagittal plane had significant interaction between fish and fin (P<0.0001). The subtle variation in these variables between animals suggests a fine-tuned adjustment of fin area and kinematics to maintain a steady gait.