Used in Chinese dishes to add texture, fish maw is the inflatable bladder in fish that allows them to ascend and descend in the water.
Most commercially sold fish maw comes from the conger pike, although all fish have the organ. After harvesting, fish maw is dried and then deep-fried. The resulting product is cream colored and resembles a sponge. Fish maws should be soaked in water for several hours before using and some recipes call for washing in vinegared water to remove any fishy odors. Although flavorless on its own, fish maw readily absorbs flavors and is considered a delicacy. One of the most common uses for fish maw is in fish maw soup.