The foil on the foam board is a vapor/moisture barrier, slightly bevel the edges of the foam board so the foil side is larger and to the room side.
Unless you are running the tanker so hot that you are boiling the fish, or have a humidifier in your duct work, the dry air in CO. Should suck up most of the moisture put out by evaporation from the tank. And of course spacing the tank away from the wall.