On page 87 of Irene Thornburg's second "The Big" reference book on salt and pepper shakers series you can find the top three sets photographed as a complete series. However, we believe a fourth set belongs in this series.
On the left is a pair of dolphins that matches exactly with the characteristics of the fish above. They are slender in shape with a similar curved body and position/placement. The eyes are identical including small triangular white spots in the pupils. Of course they are wearing hats as well. What you can't see in the photo is that they are identical in size and share the same pour hole pattern - 5 and 3 pour holes.
The set is also generically marked "Japan" as the other sets. Circa 1950s-60s.