From the WD40 site
What a Fish story!
Myth: WD-40 contains fish oil.
Consumers have told us over the years that they have caught some of the biggest fish ever after protecting their fish hooks and lures with WD-40. We believe this legend came from folks assuming that the product must contain fish oil since it appears to attract fish. Sorry Charlie®, it just aint so.
WD-40 Company has taken steps to respect and conserve the environment, and encourages its users to do the same. While WD-40 can be used to help protect fishing equipment from rust and corrosion, WD-40 Company does not recommend using WD-40 to attract fish.