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Antioxidants play a crucial role in maintaining health by scavenging free radicals that causes cellular damage and accelerates aging and disease. The present study focuses on the antioxidant levels in various organs of Hilsa fish, both male and female, with a weight range of 50 g to 780 g collected from the Hooghly River in the lower Gangetic plain. The study utilized commercially available free radicals such as, viz., 2,2′-azinobis-[3-ethyl-benzothiazoline-6-sulfonic acid] and ferric reducing antioxidant potential to measure the scavenging activity. The results indicated that female Hilsa fish possess higher levels of antioxidants (93.79 ± 0.26) compared to male counterparts (84.50 ± 0.65) in all organs, with levels increasing proportionally with weight. Interestingly, in males, the serum antioxidant profile was higher in the lower weight group (50–100 g), whereas, in females, the highest antioxidant activity was observed in the weight range of 300 g to 400 g. The present study was attempted for the first time to characterize the antioxidant distribution pattern in the different organs of Hilsa. These findings suggest that Hilsa fish organs, including serum, contain high levels of antioxidants that could significantly benefit human nutrition and potentially will contribute to anti-aging effects by incorporating Hilsa to their diet, which needs further clinical study.

The Hilsa, Tenualosa ilisha, commands a very high value as food fish. The present study was carried out to understand the breeding phenology of T. ilisha in relation to climatic variables. Monthly fish samples were collected from two landing centres, namely, Uzanbazar (Guwahati) and Shri Ramghat, Dhubri, of River Brahmaputra during May 2018 to April 2019. The assessment of gonadosomatic index (GSI) of T. ilisha revealed higher GSI values during October to February, and showed temporal variations with respect to sex. In males, highest GSI value was observed in the month January followed by February, whereas in females, GSI value was found to be highest in November followed by October. GSI (pooled) value was negatively correlated with air temperature, indicating vulnerability of the species to climate change. The highest percentage of mature males was observed during October–February, and mature females during October–December. The length at first maturity was recorded to be 290 mm for female(s) and 259 mm for male(s). The absolute fecundity ranged from 103,164 to 583,456 ova for fishes in the size range of 229–403 mm, with an average of 250,532 ova per female. Relative fecundity was found to range from 306 to 1096 ova per gram body weight, with an average of 791 ova per gram body weight. The diameter of ova of the studied fishes ranged from 414.6 to 738.2 µm, with a mean value of 546.73 ± 7.18 µm. The percentage frequency distribution of mature ova shows a distinct single peak or mode. Sex ratio (male: female) was found to be 1:0.87, indicating dominance of males over females. The chi-square test on observed sex ratio against the hypothetical ratio of 1:1 did not reveal a significant difference (p > 0.05). The findings of the present study can provide impetus toward successful management of this highly prized, transboundary, and migratory resource of River Brahmaputra, in the context of changing climate.