Motility, viability and fertility of goldfish Carassius auratus (Pisces: Cyprinidae) post short-term cryopreservation.

BACKGRUND: Goldfish Carassius auratus is a popular ornamental fish extensively cultured worldwide. Sperm cryopreservation is a common fish breeding method that ensures sperm availability around the year. Studies on cryopreservation of goldfish sperm, especially on the suitability of cryoprotectant types and pre-freezing time, are scarcely available. OBJECTIVE: To determine the most suitable type of cryoprotectant and pre-freezing for the successful cryopreservation of goldfish sperm. MATERIALS AND METHODS: A completely randomized design with two factors was utilized in this study. The first factor is the type of cryoprotectants, which included methanol, ethanol, ethylene glycol, glycerol, and DMSO. The second is pre-freezing times of 10, 20, 30, and 40 min at each of the pre-freezing temperatures of 4 degree C, -10 degree C, and -79 degree C, meaning that the total times for the ramping down of temperature were 30, 60, 90 and 120 min, respectively. The Ringer solution and 10% egg yolk were used as extender and extracellular cryoprotectant. The sperm was stored at -179 degree C for 7 days. RESULTS: The ANOVA test showed that cryoprotectants and pre-freezing significantly affected the motility, viability, and fertility of goldfish sperm after freezing in liquid nitrogen for 7 days (P<0.05). Furthermore, 10% DMSO combined with 15% egg yolk with an pre-freezing time of 20 min can maintain sperm motility, viability, and fertility higher than other treatments, by 79%, 80%, and 33%, respectively. The agarose gel electrophoresis showed no DNA fragmentation in all samples, including fresh sperm. CONCLUSION: We conclude that 10% DMSO combined with 15% egg yolk and 20 min pre-freezing is the best treatment for goldfish sperm cryopreservation. DOI: 10.54680/fr23310110412.

Improvement of sperm quality of the depik fish, rasbora tawarensis, after cryopreservation using antioxidant.

BACKGROUND: The cryopreservation of the sperm of the depik fish, Rasbora tawarensis, has previously been developed. However, the quality of the sperm post cryopreservation was not satisfactory and might be improved through the application of antioxidants. OBJECTIVE: To determine the most suitable antioxidant for the cryopreservation of the depik fish spermatozoa. MATERIALS AND METHODS: A completely randomized design with a non-factorial experiment was used and the tested antioxidants were glutathione, beta-carotene, ascorbic acid, and butylated hydroxytoluene (BHT) at 6 % concentrations. All treatments had three replications. The sperms were collected from 10 male fishes and diluted with Ringer solution in a ratio of 1: 20 (v/v, sperm: Ringer solution). Then 5% DMSO and 5 % egg yolk were added to the diluted sperms. Furthermore, 6 % of the tested antioxidants were added to the diluents, and then, cryopreservation was carried out in liquid nitrogen for 14 days. RESULTS: The ANOVA test showed that the application of antioxidants significantly affected the sperm motility, fertility, and hatching rates of the eggs (P < 0.05). Furthermore, the antioxidants also protected the sperm cells during cryopreservation, with glutathione being the best antioxidant. CONCLUSION: The application of antioxidants during the cryopreservation of depik fish sperm had a significant effect on motility, fertility and hatchability of eggs post-cryo. Furthermore, glutathione was the most suitable antioxidant. doi.org/10.54680/fr23110110312.