Optimisation of sperm cryopreservation protocol for Asian stinging catfish Heteropneustes fossilis (Bloch, 1794), to support hatchery seed production

The present study experimentally evaluated different parameters such as extender composition, storage duration and egg to sperm ratio to optimise parameters for sperm cryopreservation in Asian stinging catfish Heteropneustes fossilis. Four extender compositions viz. Hanks Balanced Salt Solution (HBSS), Modified HBSS (M-HBSS), Modified HBSS with hen’s egg yolk (M-HBSS with EY) and European catfish extender were evaluated for sperm cryopreservation with dimethyl sulphoxide (DMSO) as cryoprotectant (10% v/v). The hatching rate was used as standard to evaluate the fertility of thawed sperm at different periods of storage (2, 270 and 668 days). After 2 days, extender M-HBSS exhibited highest hatching rate (49.06±2.67%) which was comparable to the control value (51.00±7.23%), followed by HBSS (42.76±32.0%), M-HBSS with EY (37.46±24.34%) and European catfish extender (29.47±25.61%), respectively. After 270 days with M-HBSS, hatching rate was 64.34±8.84% similar to the control; however, cryopreserved sperm with other extenders exhibited lower hatching rate as compared to control and M-HBSS. After 668 days, sperm cryopreserved in the extender M-HBSS, only yielded successful hatching. Results indicated that presence of egg yolk in the extender M-HBSS did not improve the performance of cryopreserved sperm. The successful hatching using cryopreserved sperm after 270 and 668 days of storage indicates M-HBSS as a useful extender for sperm cryobanking and seed production of H. fossilis. Keywords: Aquaculture, Cryopreservation, Cryoprotectant, Dimethyl sulphoxide, Extender, Hanks Balanced Salt Solution, Hatching rate