What did you bake in? Your normal map generally will not "align" at the seams when looking at the texture as a flat diffuse, its just not how normal maps work. The color a pixel is in your normal map is a combination of a bunch of things, highpoly angle, smoothing(lowpoly mesh normals), uv direction etc etc.
Sorry I should have mentioned that I have tried that. The tail in the normal map is upside down compared to the body and I have a feeling this might be the issue however I have isolated it, inverted green and red channels (separately and together) and it is still messed up. I even applied the normal map as a diffuse to see…