A thicker tail root
What changed
- Before: behind its widest point the body tapered to 18% of its width at the tail root, so every koi had a thin stalk before the tail fin.
- After: the body tapers to 38%, and the tail fin flares out from that width. The taper starts at the same place and follows the same curve, so the head and shoulders are unchanged.
The code
A test now checks that the tail root is between 30% and 45% of the body's width, and that it is the narrowest point between the body and the tail fin.
