My dad has a gold fish pond in his back yard. Before he goes all out and buys bait, hooks up the boat etc he will go out and throw some food in the water. If they inhale it he's on the water pretty fast. If they don't he will usually just go bank fishing with slow results. He said if he takes the boat out and they don't eat then it's always been a real bad day so why waste gas to tow the boat.