I squirkled some color onto the page with Sharpie Brush Tips. The orange was placed for a sense of flow, but wasn't necessarily meant to indicate the placement of fish.
I glazed over the page with a thin layer of Metallic Green Acrylic Paint.
I added strips of washi tape at random around the page. At this point, I'm adding layers of texture, but still not planning where my fish will go. I put very little thought into this piece--I just used techniques I'm familiar with and let it happen. (However, I later found that I had been following a certain flow--thats the result of experience. You start doing things with your composition, automatically.)
Once dry, I coated everything with a layer of Decoupatch-sort of a cross between transparent gesso and gel medium. Either of those two would also have worked. I wanted a medium that would even out the different textures and make a surface that can be drawn on, and more layers added. (Sorry for the rotation. The photo is in the correct direction but blogger insists on turning it sideways!)
I glazed the page with Metallic Blue, but not over the fish, except for an occasional stripe. Glazing simply means applying a thin, transparent layer of color over other colors. The layer should be so thin that the layers below show through, but are subtly changed, not just in color, but also in intensity. In this case, I added a touch more blue to the overall green, and darkened it just a bit. This made the fish, by comparison, brighter and greener. The stripes I added here and there, gave the impression that the fish were 'in' the water, not 'on' the water. The layers of the more transparent washi tape (the red &blue dotted type) also helped with this impression.
If you look closely, you'll also notice that with this layer of glazing, I left fish shapes that I had not drawn with pen. I made the shapes rough and not always complete. This gives the impression that there are fish deeper and farther away, adding more depth. (Not all the shape show up well in the scan).
For the last step, I used a white Sakura Gellyroll pen to add the foam, eyes, fins and bubbles. The pen then rolled off the table, and I couldn't find it for a few days, so I don't have a photo for that, lol--you can see it in the finished piece though.