balloon fish

(Zool.) A fish of the genus Diodon (such as Diodon holocanthus) or the genus Tetraodon, having the power of distending its body by taking air or water into its dilatable esophagus. It is similar to but smaller than the porcupinefish. See Globefish, and Bur fish. [ 1913 Webster + WordNet 1.5 ]