Tor soro Valenciennes , 1842, is one of endemic fish in Indonesia, which is located in North Sumatera and West Java. The local name of this fish in North Sumatera is “ikan Batak”, while in West Java which is called it as “ikan Kancra” or “ikan Dewa” (God Fish). Ikan Batak or ikan Kancra is usually used as traditional ceremony in North Sumatera, besides as a fish consumption in West Java. The population of this species in the natural habitat was significantly declining. Some factors involved in declining of this fish, such as over exploitation, lack of high quality of broodtock, and asynchronous gonad maturation . Cryopreservation, therefore is one of the methods to overcome this problem. Cryopreservation is a long-term storage method conducted in very low temperature . This method usually is applied for germ and embryo cells. A major factor which supporting cryopreservation is cryoprotectant . Cryoprotectant is a substance that protect the cell from ice crystallization during cryopreservation. In this study we used two types of cryoprotectants , namely methanol as a permeating cryoprotectant and egg yolk solution as a natural non-permeating cryoprotectant . Hence, the objective of present study was to determine the best combination of egg yolk solution of free-range chicken and methanol for 48 h storage of T. soro spermatozoa.
One level of methanol (10%) combined with six levels of egg yolk solution (0%, 5%, 10%, 15%, 20%, and 25%) were tested in this study. Fish Ringer’s solution was used as an extender. The diluted sperm were equiliberated at 5 ? for 10 min. and then kept at – 10 ? for 48 h. Sperm was thawed for 1 min at 40 ?. The one-way ANOVA showed that combination of methanol with several concentrations of egg yolk solution of kampong chicken had a significan effect on spermatozoa viability and fertilization rates (P<0.05). The study revealed that 5% of egg solution combined with 10% methanol resulted in the highest rates of viability (82.13 ± 1.75%) [Fig. 1] and fertilization rates (92.96 ± 1.94%) [Fig. 2]. Conclusion: A 5% of egg yolk solution of combined with 10% methanol in fish Ringer’s solution was the best cryoprotectant for T. soro spermatozoa preserved at -10 ?.