Free images results:

Fin pictures, stock photos and images


Fish Stock Images
Author: Lionel319

Also, here are some commercial RF-licensed images that match your search criteria:  
Surf Fin Royalty Free Stock Photo
Author: Photocpl
Tail fin Stock Image
Author: Babar760
Fin Whale Stock Image
Author: Jg1153

Explore more commercial options: More Fin Stock Illustrations & Vectors | More Fin Stock Video Footage