To animate the tail along a motion path you're going to need a curve. You can create one by going to Create > Curve Tools > EP Curve Tool. If you ever want to edit the curve, select it and press F8 to go into component selection mode and you can move the points around.
Next you want to create a locator (be sure to rename it). Then you select the locator first and the curve second. Go to Constrain > Motion Paths > Attach to Motion Path. The locator should now follow the curve.
The next step is to parent the Tail Anim to the locator. Select the Locator first, then the Anim second. Go to Constrain > Parent (options). Uncheck maintain offset and click apply. Now the anim should follow the locator which is following the path.
If the tail is facing the wrong direction, select the Locator and go to your channel box. Under INPUTS there should be something called motionPath1. Click it to expand it. Play around with Front Twist, Up Twist, and/or Side Twist to align the tail correctly.
You will also notice that the U Value is keyed. That is the value you want to animate to move the tail on the path. 0 means the start of the curve, and 1 is the end of the curve. You have to key that attribute on the current frame before you can change its value. You always have finer controls in the graph editor.