You can purchase Duck/Swan Food for $1 a bag at any of the Marie's Mini-Mart locations.  All proceeds from the sale of the Duck/Swan food go back into development projects for the  park.

The Foundation recommends not feeding bread to the ducks and the swans. Bread has little nutritional value; it dehydratees the birds because of its high salt content and it promotes bacteria growth in the water in ponds and rivers. By purchasing the proper food you will provide good healthy food to the ducks and you will not foul the water. 

Please note that during the weekdays in May to August, you can also purchase duck/swan food at The Lodge (which is located close to the Duck Pond near Bowring Park's East Entrance).