There is a spray special for finishing watercolors for a presentation without glass, but it contains hazardous chemicals so I do not use it even though there would be no pick up smearing of paint.
Next when the gloss medium is dry, I will brush on more medium. I can still work on the eye that got mushed on the first coating. Then I plan to glue this canvas board to a small box and attach a wire for hanging. When hung on the wall it will appear to float in front of the wall. The gloss finish and the appearance of floating out from the wall both suit the abstracted underwater ocean-scape subject.