Larval rearing of hilsa shad,Tenualosa ilisha(Hamilton 1822)

Abstract

Hilsa, Tenualosa ilisha has received much attention for culture due to decline of the natural population. Lack of knowledge on larval rearing is the bottleneck for its culture. This study was aimed at developing larval rearing protocols for hilsa shad. Hilsa larvae (4 days old, 4.76 ± 0.06 mm/0.49 ± 0.01 mg) were stocked in fibreglass-reinforced plastic tanks (1.7 m3 water volume) at 300, 600 and 1,200 nos/m3 in triplicates in three experimental systems viz., E-I (circular, 0.567 m water depth), E-II (circular, 0.962 m water depth) and E-III (rectangular, 0.567 m water depth) and reared for 46 days. The larvae were supplied with Chlorella vulgaris, Brachionus calyciflorus, mixed phytoplankton and mixed zooplankton during 4–50, 6–25, 8–50 and 26–50 days of their age respectively. In each system, higher (p < 0.05) fry survival at 300 nos/m3 than in higher densities indicates density dependent stress. Circular tanks showed higher survival (13.3%–61.31%) than in rectangular tanks (6.88%–27.26%) in each stocking density, indicating the importance of tank shape for rearing. Water depth affected fry survival in circular tanks (E-I and E-II) at 300 nos/m3; at 0.962 m depth, survival was higher (61.31%, p < 0.05) than that of 0.567 m depth (49.93%). Good fry survival was achieved through feeding the larvae initially with Chlorella followed by co-feeding with Brachionus, mixed phytoplankton and zooplankton and rearing in circular tanks at 300 nos/m3 densities at 1 m depth. This first-ever larval rearing protocol is useful for mass production of fry to support hilsa aquaculture in future.