The reproductive cycle of the fresh water fish Labeo bata (Hamilton) (Cypriniformes: Cyprinidae)

Abstract

A total of 2200 specimens of Labeo bata (Ham.) were collected from rivers, beel and ponds of different local areas of Rajshahi region of Bangladesh during February 2007 to January 2009. For the study of reproductive cycle of L. bata, 1263 females (mature and immature) were used and the reproductive cycle was estimated. From this observation it was obvious that September to March was the breeding season but Peak in June to August for this species. Further observation reveals that no gravid female was found during the months from October to January of this study period. It was found that L. bata spawns once a year. The species is considered as major fresh water (Small indigenous species) fish in this country. So it is regarded as an excellent food for the people.L. bata, because of its fresh water nature it received no attention in the scientific literature despite of its prominence among the fresh water fish and economic importance in the Indo-Pak-Bangladesh sub continent. It may also be mentioned here that no work has been done on reproductive cycle of this fish till now in this country although several workers have made significant contribution to the reproduction cycle in different fishes Alikundi ( Sexual developments involve the maturation of structural, physiological and behavioral machinery concerned with mating and reproduction and controlled by sex hormones (Charniaux 1954, Adiyodi andAdiyodi 1974). It is evident that like all other population of fishes, L. bata is on the decrease due to natural and other factors. A study of reproduction biology of L. bata is found to be essential in the sense that it may provide information and clues for a tactful and skilful culture and fishing of this species. The present study is aimed at providing a comprehensive account of the reproductive biology of L. bata.Reproductive behavior in fishes is cyclic more or less regularly periodic (Lagler et al. 1967). The reproductive act in some fishes occurs only once in a very short life time, while in other fishes, it occurs in moderately long life span. Several other species spawn more than once in a year more or less continually. After spawning new group of oocytes is formed, which gradually mature to become ready for the next season.Reproductive cycle of fishes depend upon several factors. Both light and temperature are important factors in controlling the maturation of gonads in fishes. Variation in the duration of light and temperature may influence the rate of gonadal development. According to Kinne (1971), most of the stages of reproduction often depend on certain condition of water movement. In rainy season particularly in June and July months after a heavy shower, the physico-chemical condition of water bodies abruptly changes and which in turn probably  Corresponding address E-mail: raz2006_ru@yahoo.com Joadder 138 stimulates spawning in most of the freshwater fishes (Jhingran 1977). Total length and ungutted weights of the fish were recorded to the nearest 1mm and 1g with the help of an electronic balance (Mfd. BY ...