An artist here used to airbrush any fish you could give her a picture of, onto Tee shirts. They needed special care the first time you washed them. If you are airbrushing a design on the outside back of the tank, it should work OK, but I'm not so sure about airbrushing a foam background. If there are air brush compatible paints that could hold up to water and not affect the fish, the background would still be very bouyant without the counterweight of a mortar coating.