1Make and bake cake mix as directed on box for 13x9-inch pan, using water, oil and eggs. Cool. Line 2 cookie sheets with waxed paper. Crumble cake into large bowl. Add frosting; mix well. Shape into 1 1/4-inch balls; place on 1 cookie sheet. Freeze until firm; keep refrigerated.
2In 3 separate bowls, stir each color melted candy and 1 tablespoon shortening until smooth. Spoon 1/4 cup of each color candy into separate resealable food-storage plastic bag; seal bag. Cut off small corner of bag; squeeze bag to pipe fish fins onto prepared cookie sheet. Refrigerate 5 minutes.
3Dip tip of 1 lollipop stick about 1/2 inch into melted candy and insert stick into 1 cake ball no more than halfway. Return to cookie sheet. Refrigerate 5 minutes. Remove from refrigerator 1 at a time. Dip cake ball into melted candy to cover; tap off excess. Coat with sanding sugar. Immediately attach candy fins, cereal for mouth and confetti for eyes. Poke opposite end of stick into foam block. Let stand until set.