Effect of extender composition on sperm cryopreservation of Asian catfish Heteropneustes fossilis (Bloch) and Clarias batrachus (Linnaeus)

Air breathing catfish species Heteropneustes fossilis (Bloch) and Clarias batrachus (Linn.) are important table fish and fetch high market price. Cryopreservation of spermatozoa can be a useful tool in captive seed production for domestication and aquaculture of these catfish species. The objective of the present study was to identify optimum extender composition for sperm cryopreservation of the two species, Heteropneustes fossilis and Clarias batrachus. Four extender compositions Hank's Balanced Salt Solution (HBSS), Modified Hank's Balanced Salt Solution (M-HBSS), Modified Hank's Balanced Salt Solution with hen's egg yolk (M-HBSS with EY) and European catfish were evaluated for cryopreservation of catfish sperm and 10 % Dimethyle Sulphoxide (DMSO) was used as a cryoprotectant. The pooled milt exhibiting 70-80% motile sperm was used for cryopreservation experiment. After storage for 48 hrs at -196 degree C, the milt was thawed and evaluated for fertility test. The percentage of hatching was used as a parameter for the comparative evaluation of different extender composition. In Heteropneustes fossilis extender M-HBSS indicated highest hatching rate (49.06%), followed by HBSS (42.76%), M-HBSS with EY (37.46%) and European catfish (29.47%). The hatching success with extender M-HBSS did not differ significantly (P > 0.05) from the control group (51%). In Clarias batrachus extender HBSS exhibited highest hatching (62.1 %), followed by M-HBSS with EY (51.6%), European Catfish (46.3%) and M-HBSS (40.9%). The hatching rate in control was 90% in Clarias batrachus. The results indicated that the two species differ in the protocol for sperm cryopreservation. The paper presents successful cryopreservation of sperm with the production of viable hatchlings of Heteropneustes fossilis and Clarias batrachus for the first time. The protocol reported in the study can be used for scaling up of seed production of these two catfish species.