If it were me, I would say it is more of an arrow spin issue instead of a bow issue. Go with a lighter spin or heavier point and see if it makes a difference. When you say it is fish tailing, i would assume the arrow is to stiff and not bending around the riser. This would cause it to bend back to early and wacking the riser when the arrow passes by, causing it to fish tail in flight.
If you have too light of a spins, it could be bending too much and not recovering quick enought to get around the riser. If this is the case you need a bit stiffer spin or less head weight. This
With all that said, it could be form problems (not saying your form is bad, just another suggestion). Reason I am inclined to say what I have mentioned is because I have made bows with center cut shelves pretty much to the midline and once I got the right spin arrow, they shot like dart.