In my last Reader's Cast article I wrote about how we perceive objects in our environment. Our brains rely on shape and behavior to quickly identify objects that we encounter. We don't need to stare intently at objects that we routinely encounter in order to identify them. Likewise, it seems logical that fish use the same system when determining if something they encounter is food or not. If it has the general shape of a food item and it moves like a food item then it must be a food item. However, what about color? How does the color of the object affect their reaction?