The indianapolis zoo does have an Aquarium. As far as your budget is concerned i'd take her to the Weber Grill at illinois and Washington on the NW side of the street. All the food there is cooked on Weber charcoal grills and is very flavorful. Should run you right at $40 for 2 unless you'll be boozing it up. If you like Thai food, Siam square just N of fountain square on Virginia is really good and should run you 30-40 for 2. Sushi is out as far as downtown is concerned. Trust me on the Weber Grill. You'll also be walking distance from the carriages.