Ditto this.If it's a bikini-like tube top (i.e., teeny weeny!), then IMO it would need an outer layer to cover up a bit, perhaps a cardie or a fitted Sienna Miller-like vest. But if it's an actual top that covers your stomach, then you probably don't need an outer layer...unless you would like to have the option of toning it down with a little short-sleeved cardie (would be my personal preference!).
Thanks all for your replies. It's a relatively long tube top so it covers my body except for the shoulders.
Venusfly, it's not tight tight but fitting. In your opinion, does that still fly?
Snibor, I would prefer a tank too but the tank I saw is really short and shows the stomach.
It sounds kinda tacky to me, but I'd have to see a picture to know for sure!