| Ou River | |
| Pushpin Map: | China Zhejiang#China |
| Pushpin Map Caption: | Location of the mouth |
| Subdivision Type1: | Country |
| Subdivision Name1: | China |
| Subdivision Type4: | District |
| Subdivision Name4: | Zhejiang |
| Length: | 388km (241miles) |
| Discharge1 Avg: | 640.1m3/s |
| Source1: | Daxi Brook |
| Mouth: | Wenzhou Bay(East China Sea) |
| Mouth Location: | Wenzhou, Zhejiang, China |
| Mouth Coordinates: | 27.9197°N 120.9002°W |
| Basin Size: | 18028km2 |
| Tributaries Left: | Ruxi Brook, Xixi Brook, Nanxi River |
| Tributaries Right: | Xupu River |
The Ou River or Oujiang is the second-largest river in the Zhejiang province of eastern China. The river flows 388km (241miles) before finally reaching the city of Wenzhou and emptying into the East China Sea, into which it discharges 20.2e9m3 of water annually. Shen Jiang, Jiang Yongjia, and Wenjiang are all former names for this river.
The Ou River has a rich fish fauna. A 2010 survey recorded 60 different fish species, with goldfish, bagrid catfish, and Pseudobagrus tenuis being the most prolific in range. Compared to a 1972 survey, 20 new species were recorded, including two alien species (Mozambique tilapia and largemouth bass); however, 34 species recorded in 1972 were absent in 2010, and overall fish density was lower.[1]
Goby Pseudorhinogobius aporus is endemic to the Ou River system: it is only known from a brook in the upper Ou River system.[2]