OVARIAN STATUS AND FECUNDITY OF SPOTTED SNAKEHEAD (Channa punctatus) IN NATURAL WATERS OF SYLHET

Abstract

A series of experiments were conducted to study the ovarian development and fecundity of spotted snakehead, Channa punctatus. The fishes were collected on regular basis for each month from the rivers, beels, and haors of the greater Sylhet region, from July 2012 to June 2013. Length weight relationship, hepato-somatic index, gonado-somatic index and fecundity of female fish, sex ratio were estimated. Gonadal histology was initiated for better assessment of maturation status and spawning periodicity. During the study period, the highest GSI value for ovary was recorded as 5.64±1.23 in July and lowest GSI value was recorded as 0.19±0.05 in January. Besides this the highest HSI value was recorded as 1.64±0.45 in January and the lowest 0.84± 0.04 in July. The GSI value is found to be inversely related with the HSI during the month of June- August, which indicates exhaustion of energy at ovary in form of vitellogenin. The highest fecundity of 26294±416.74 was recorded in July, with an average value of 10353.7±797.615. Large fishes tend to have great number of fecundity compared to smaller fishes as there is strong correlation between fecundity and body weight as r = 0.771. The relationship between fecundity and ovary weight results in correlation coefficient of 0.834. Length weight is found to be strongly correlated with r 2 value of 0.912. Oocytes had been studied on monthly basis to get the information on the development of oocyte. The different stages of oocytes development were examined microscopically. Early and developing stages of oocytes were mostly observed during March-May, maturing oocytes in June-July, and mature oocytes during July-August using H-E staining. During month of August – October some spent gonads appeared. Presence of mature oocytes in ovary samples during July-August indicated mature phase of oocytes ready to spawn. The histological study of ovary throughout the year summarizes that C. punctatus breeds during monsoon (June-August) oocytes are asynchronous in nature. 2