I found the idea while perusing the Family Fun website.
Fishing Pond Snack
1/2 block cream cheese, softened
Blue food coloring
Fish shaped crackers
Mix blue food coloring into the cream cheese until smooth. Put into a shallow bowl. Add fish crackers around the "pond" or you could put them into a separate bowl. Use the celery sticks as fishing rods by dipping them into the cream cheese and then "catching" the fish crackers.