I love Antwerp!
Well, there is always Chez Leon (it is a restaurant chain, but good quality) for moules frites.
There are heaps of great restaurants in Antwerp (Belgian food is good), it might be worth asking around once there:
tFornuis gets good reviews, and is more pricey:
LATIN QUARTER. A 16th-century stone house in Antwerp's historic section is the setting for this revered restaurant. Sturdy oak chairs and low-beamed ceilings create a cozy ambiance, and although there are no menus, the chef comes by your table to explain the day's selections. Representative meals feature sole with rhubarb or roasted sweetbreads in wild truffle sauce; a 4,000-bottle wine cellar provides apt accompaniments. Take time to admire the restaurant's collection of miniature stoves. Reservations necessary. Business-dressy attire.
Reyndersstraat 24, Antwerp, Belgium · 323-233-6270
From this website which lists some other great places too:
here