Chowhounds in the San Francisco Bay Area recently enjoyed a Shanghai feast at Su Hong Eatery in Palo Alto, including a sweet and sour squirrel fish prep (illustrated below). Its called a squirrel fish because the method of cross-cutting the flesh and then deep-frying opens up the body and positions the head and tail erect like a squirrel. There was some debate at the table over what kind of freshwater fish was used to make this dish. The restaurant owner was able to tell us that its Chinese name is guei yu.
Replies to the post linked below have provided enough clues to come up with the answer. ScottM pointed us to the aucha perch (with a photo) found in Japan and many regions of China as a possibility. Chibi identified guei yu as the freshwater Mandarin fish, also known as Osmanthus fish, and linked to an illustration. Gary Soup also indicated Mandarin fish in the New Bamboo thread on this board.
A web search turned up more information on freshwater Asian perches in the family Serranidae. Mandarin fish (or the Chinese perch) is Siniperca scherzeri or alternately Siniperca chuatsi. It is a close relative of the Japanese aucha perch, Siniperca kawamebari, and the Korean aucha perch, Coreoperca herzi.
Additional information on squirrel fish and Mandarin fish are included in the replies to this post.
Image: [BROKEN LINK REMOVED]