Abstract: Investigations on the biology of a small-sized commercial fish,Neosalanx pseudotaihuensis were carried out in Yuni lake of Hubei Province from March 1992to Mav 1993.This fish is a kind of zooplankton feeder,feeding mainly on Cladoceraand Copepoda. It grows fast and reaches 68.7 mm in average total length and 0.70gin average weight within only one year.The one year old fish become sexuallymatured,and the spawning took place from the end of March to the first ten daysof June with prosperous spawning occurring during the first ten days of April andof May. After the spawning of the first batch of eggs,ovaries of the fish regeneratedinto Stages Ⅲ-Ⅳ,and continually developed rapidly into Stage Ⅳ and Ⅴ. Thefish were thus ready for a second spawning.It is obvious that the fish is ofmultiple spawning type.After the last spawning,the parent generation died off.The lifespan of the fish lasts one year only.The rational fishing season for thisfish should be among the winter. But reserved zones lnust be set up in the lake tostock part of the generation which will reproduce next year. However, during theperiod reproduction fertilized eggs or artificially hatched fries should be stocked.