Population growth (length-weight relationship), and reproductive potential (e.g. fecundity, and sex-ratio) of five important fish species (‘mola’:Amblypharyngodon mola, ‘puti’:Puntius sophore, ‘tengra’:Mystus vittatus, ‘shing’:Heteropneustes fossilis and ‘taki’:Channa punctatus) collected from two important fresh water bodies (namely Hilna beel and Beel Kumari beel) Rajshahi, Bangladesh, were studied. Population growth pattern by length-weight relationship (W=aLb) for the species differed, and exhibited positive allometric growth (P. sophore in Hilna beel), isometric growth (A. mola andC. punctatus in Hilna beel) and negative allometric growth (M. vittatus&H. fossilis in Hilna beel andA. mola,P. sophore,M. vittatus,C. punctatus andH. fossilis in Beel Kumari beel). The results denoted that fecundity of mature females followed a non-linear relationship (F=aLb) with total length and exhibited positive allometric growth (b>3) with some exception (A. mola in Hilna beel andM. vittatus in Beel Kumari beel). Fecundity of mature females also increased with total body weight and ovary weight following a linear relationship (F=a+bW). Differences in values of sex-ratios with seasons for all species in this study may have resulted from different environmental factors as well as breeding seasons. The findings of this study would be useful in imposing adequate regulations for the conservation of these fascinating fishes in the fresh water bodies of Bangladesh.

Keywords: Beel, Fecundity, Sex-ratio, Length-weight relationship, Small indigenous fish