Some observations on the biology ofCirrhinus reba(Cuvier) from Muzaffarnagar (U.P., India) have been made during the period July 1966 to June 1969. InC. rebaboth males and females mature simultaneously. The gonads attain the maximum weight in June and minimum in November. There is a definite seasonal cycle in relative condition. The relative condition in both male and female is highest in June preceeding the period of breeding. It is the gonad weight which influences the fluctuations of the relative condition. The visceral weight does not exert any significant effect on it. It is found possible to determine the spawning season and its extent, from the seasonal fluctuations of the relative condition. The present studies have also thrown light on the maturation and spawning habits ofC. reba. The fish has only one spawning season of short duration, running from July to early September. In a mature ovary, the mature ova form only one mode which is sharply distinguished from the immature stock.