Goldfish are one of the most popular pets for kids, according to the Association of Mature American Citizens [AMAC]. They are easy to take care of and hardy enough to live as long as ten years. They grow to a manageable six inches in a tank. How big can they grow in a lake, for example? A British angler recently landed a monster of a goldfish in a lake in Champagne, France. It weighed in at 67 ...