大口鳒，俗名皇帝鱼，为辐鳍鱼纲鲽形目鳒亚目鳒科的其中一种。

本鱼分布于印度西太平洋区，包括东非、南非、塞舌尔群岛、马达加斯加、毛里求斯、波斯湾、斯里兰卡、印度、巴基斯坦、伊朗、孟加拉、缅甸、马来西亚、越南、泰国、柬埔寨、日本、中国、菲律宾、印尼、新几内亚、澳大利亚等海域。

The spiny turbots are a family, Psettodidae, of relatively large, primitive flatfish found in the tropical waters of the east Atlantic and Indo-Pacific. The family contains just three species, all in the same genus, Psettodes. The common name comes from the presence of spines in the dorsal and anal fins, which may indicate an evolutionary relationship with the Perciformes. They are less asymmetrical than other flatfish, although the region around the eyes is twisted. They reach lengths of 55–80 cm (22–31 in).