The primary ingredient (over 50%) is a mineral spirit presumed to be a Stoddard solvent. Think along the lines of turpentine. Nobody outside of the manufacturer knows the exact ingredients of WD-40 because it is not patented. The company releases a "chemical safety" breakdown on the product sonly because if it didn't nobody would use it industrially.
Spraying WD-40 on your fishing line is basically water pollution. If WD-40 has fish oil in it that would have to fall in the "10% inert" part of the ingredients.