The bubbles "showed up" when I spritzed Murphy's Oil Soap, mixed half and half with water, onto the wet paint. By tipping the paper slightly, I was able to suggest a lot of movement in the water.
I made sure the fish area was a darker shape while all the paint was still wet. I'd miskited the white lines on the the fish before I ever added paint to the YUPO surface, and it was easy to lift off the miskit after the paint dried by using some rolled up masking tape.
Final touches were to paint in the details needed on the fish. Oil and water don't mix, but they sure helped make a believable deep blue sea!
"DEEP" Transparent Watercolor on YUPO 26 x 20"