Going Fishing -- There is an amazing abundance of fish in the Upper Amazon. The lakes and rivers are an endless source of food, with more than two thousand species of freshwater fish. There are catfish of all sorts, especially the delicious dorado, which can grow to a hundred pounds in deep river channels and oxbow lakes. And there is paiche -- the largest freshwater fish in the world, whose flaky and delicately flavored flesh has been featured in Gourmet Magazine. Here's how to catch them.