Some Aspects of Biology and Biochemical Composition of Channa punctatus (Bloch, 1794)

Abstract

To study the biology of the snakehead, Channa punctatus in Khulna region, sex ratio, monthly changes in GSI and fecundity were observed in the-Laboratory. Male-female ratio of the studied species was 1: 0.57. Fecundity of the fish ranged from 2274 to 9795 in fishes total length ranged of 18-15.5 cm, The fecundity is more directly related to the ovary weight The regression line of fecundity in total length, standard length and gonad weight were all found to be linear and their co-efficient were all positive and significant (P<>O.05). But the regression line of fecundity in body weight was negative. From their monthly dynamics in GSI, spawning seemed to have taken place somewhere between May to June with a peak- in June for male and between May to June with a peak. in May for female. Furthermore, GSI revealed that C punctatus has a short spawning season. The effects of the parts of body, size class, sun drying, oven drying, boiling, frying, freezing and eggs on proximate composition of C punctatus were determined. Large size fishes were high in protein (19.37 ± 021 %) and fat (1.10 ± 0.03%) and low in ash (1.75 ± 0.02%) and moisture (79.64 ± 0.10%) whilst small size fish low in protein (17.77 ± 0.14%) and fat (0.73 ± 0.14%) and high in moisture (82.73 ±L03%). For different body parts, the protein content was higher in the head portion of male (19.86 ± 0.02%) than female; the lipid content was higher in different parts of male than female. The percentage of ash. content ranged between 125 and 3.54. % and among the different portions of male and female-fish, moisture content was the highest in tail (77.43 ± 0.89%)and the lowest in head (7631 ± O.09%} of male. These were inversely related to female. The protein, lipid and ash content in the fish flesh, sun dried fish, oven dried fish, boiled fish, fried fish, freezed fish and fish eggs ranged from 18.63 ± 1.29 to 66.51 ± 4.87, 0.56 ±0.45 to 30.03 ± 1.40 and 1.20 ± 0.14 to 34.17 ± 1.29%, respectively. In general dried fish and fish eggs showed higher protein and lipid content. Monthly changes in nutrient content like protein, lipid, ash and moisture were assessed in the snakehead, C punctatus in both wet weight (body flesh) and dry weight (whole body) basis from the month May 2002 to April 2003. The highest value of protein in the body flesh was found in November (22.34 ± 0.31%) for Male and in September (22.57 ± 2.02%) for female. The highest value of lipid was found in February for male (2.49 ± 0.17%) and female (2.64 ! 0.32%).The highest value of ash was found in September (2.12 ± 057%) for male and February (2.28 ± 1.04%) for female. The highest value of moisture content was found in August for male (81.36 ± 1.36%) and female (80.01 ± 0.14%). On the dry weight (whole body) basis, the highest value of protein (78.67 ± 0.35%), lipid (21.60 ± 0%), ash (34.17 ± 1.29%) and moisture (75.48%) was found in January, April, July and November, respectively for male. On the other hand, the highest value of protein (76.13 ± 0.83%), lipid (19.58 ± 0.12%), ash (28.59 ± 0.49%) and moisture (76.53%) was found in September, March, June and October, respectively for female fish. From the nutritional point of view it shows that the nutrient content of snakehead fish C punctatus is undeniable compared to other small and large fishes.