Reproductive Characteristics and Germ Cell Status of Indian Major Carp, <i>Labeo rohita</i> Reared in Elevated Water Temperature Regime

Abstract

Rearing water temperature and fluctuations in it has a profound effect on survival and gonadal development of fish. Reproduction in fish, compared with other physiological processes, only occurs in a bounded temperature range; therefore, small changes in water temperature could significantly affect this process. Here we analysed the effects of different rearing water temperatures (28 °C, 30 °C, 32 °C, 34 °C and 36 °C) and a cytotoxic drug (busulfan) on germ cell status and maturation in Indian major carp, Labeo rohita. The effectiveness of the treatment was assessed by gonadosomatic index, histology and dye uptake of GC. Thermo-chemical treatments were given either: as elevated water temperature alone (0.69±0.09) or in combination with busulfan that showed a low GSI value (0.49±0.26) as compared to control (0.88±0.009). Gonadal morphology visibly shrunk after the thermochemical treatments. Similarly, the gonadal histology confirmed that the GC depletion took place when the rohu were reared at elevated temperature along with the application of a cytotoxic drug busulfan (40 mg/kg). According to the deteriorating reproductive responses of the fish by temperature fluctuations, it is plausible that changes may affect aquaculture production and affecting future populations of fish, so new strategies for amelioration should be anticipated.