Seasonal Changes in Biology and Biochemical Compositionof Labeo gonius (Hamilton) Reared in Mini Earthen Pond

Abstract

To study the biology of small indigenous species Labeo gonius reared in mini earthen pond in the Khulna University campus, monthly changes in length-weight relationship, GSI and fecundity were observed in the Laboratory. A total of 114 species of L. gonius was collected randomly during the one year study period from September 2004 to August 2005. The equation for total-length weight relationship of the species was found to be W = 1.122TL 1.0418. The mean value of condition factor (K) and relative condition factor (Kn) for L. gonius was 229610 and 0.90 respectively. The average value of SD was found ±309780.1 in case of condition factor and ±0.88 in case of relative condition factor. The fecundity is more directly related to the ovary weight. The regression line of fecundity on total length, body weight and gonad weight were all found to be linear and positive and their co-efficient were all positive and significant at 5% level of significance except the total length-body weight relationship which was found insignificant at 5% level of significance. From their monthly dynamics in GSI, spawning seemed to have taken place somewhere between May to July with a peak in May for male and July for female. Furthermore, GSI revealed that L. gonius has a short spawning season. Monthly changes in nutrient content like protein, lipid, ash and moisture were assessed in the L. gonius in wet weight basis during the month September 2004 to August 2005. The highest value of protein percentage in the body flesh was found in February where (20.62 ± 0.509) for combined sex. The highest value of lipid % in the body flesh was found in April (9.55 ± 0.59) for combined sex. The highest value of moisture % in the body flesh was found in June (87.92 ± 1.195) for combined sex. The highest value of ash % in the body flesh was found in May (2.93 ± 0.050) for combined sex. From the nutritional point of view it shows that the nutrient content of L. gonius is undeniable to other small and large fishes.