I've been traveling and without internet, but now that I am safely in Lakeside Ohio I'm going to post Wednesday's developments.
In step one, I taped all the fish I cut out to the canvas.
Then I painted over the area:
And finally I took off the fish cutouts, revealing the underlying paint layers in contrast to the newest one.
The painting is not quite finished, but now it gets to dry for two and a half weeks while I teach art classes here in Lakeside.