I’ve been trying for years to identify this species to no avail. In Chinese, they are S: 小公鱼; T: 小公魚 (xiǎo gōng yú), which simply means ‘little common fish’. They are sold here alongside dried fish of all sizes, but are in fact deep fried whole and ungutted and sold as S: 油炸小公鱼; T: 油炸小公魚 (yóu zhá xiǎo gōng yú), ‘deep fried small common fish’. There is an indication that they are river fish, so I’m calling them ‘minnows’.
The are certainly small enough, ranging from approximately 25.4mm / 1 inch to 50.8mm / 2 inches in length.
They are added to congee and stir-fries to give a savoury taste or enhance umami.