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.

Effect of glutathione on sperm quality after short-term cryopreservation in seurukan fish Osteochilus vittatus (Cyprinidae).

The objective of this present study is to determine the optimum concentration for glutathione in the cryopreservation of seurukan fish (Osteochilus vittatus) spermatozoa. A completely randomized design (CRD) was used with 6 treatments and 3 replications. The Seurukan fish sperm was diluted in extender with a ratio of 1:20 (sperm: extender), then glutathione was added at a concentration of 0, 10, 20, 30, 40 and 50  mg L-1. Next, the sperm thawed at 39-40 °C for 3 min and mixed with 100 eggs which were randomly selected. The success of the fertilized egg was observed 6 h after fertilization, while the hatching rate was examined 60 h after fertilization. The ANOVA test showed that the addition of glutathione significant affected the sperms motility, fertility and hatching rate of seurukan fish Osteochilus vittatus eggs (P < 0.05). By segregation the fresh sperm, a higher sperm motility rate was recorded with an addition of 30 mgL-1 of glutathione (63.00 ±â€¯5.89), however, this value was not significantly different from using concentration of 10 and 20  mg L-1. A higher fertilization rate was produced using glutathione concentration of 50  mg L-1 (51.33 ±â€¯17.01); however, it was also not significantly different from the concentration of 20, 30 and 40 mgL-1. In addition, a higher hatching rate was also recorded using glutathione concentration of 50 mg L-1 (40.33 ±â€¯12.89), this value was not significantly different from using 40 mgL-1 glutathione. Hence, a conclusion was drawn that the optimum concentration of glutathione is 40 mg L-1 of diluent.

Remarkably low genetic variation but high population differentiation in the climbing perch, Anabas testudineus (Anabantidae), based on the mtDNA control region.

Anabas testudineus (Anabantidae) is an important food fish in Southeast Asia. We analyzed the mitochondrial DNA control region sequence data to evaluate the genetic variability and population structure of this species. Sixty specimens were collected from four populations in Sumatra and two populations in Peninsular Malaysia. We found a very low level of genetic variability, with five of the six populations exhibiting total absence of genetic variation. Based on analysis of molecular variance, 84.72% of the total variation was among populations and 15.28% within populations. A geographical division based on FST values indicated highly significant genetic differentiation among populations from the four drainage systems: Aceh, Sumatra Utara, Pulau Pinang, and Terengganu (FST ranging from 0.633 to 1.000). No phylogeographic relationships among populations were detected, despite the generation of four distinct clades in a neighbor-joining phylogenetic tree.

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh province, Indonesia.

BACKGROUND: Rasbora tawarensis is an endemic freshwater fish in Lake Laut Tawar, Aceh Province, Indonesia. Unfortunately, its status is regarded as critical endangered with populations decreasing in recent years. To date no information on the spawning activities of the fish are available. Therefore, this study provides a contribution to the knowledge on reproductive biology of R. tawarensis especially on spawning seasons as well as basic information for conservation of the species. METHODS: Monthly sampling was conducted from April 2008 to March 2009 by using selective gillnets. The gonadosomatic index, size composition and sex ratio were assessed. The gonadal development was evaluated based on macroscopic and microscopic examinations of the gonads. RESULTS: The gonadosomatic index (GSI) varied between 6.65 to 18.16 in female and 4.94 to 8.56 for male. GSI of the female R. tawarensis was higher in March, September and December indicating the onset of reproductive seasons, the GSI and oocyte size being directly correlated with gonadal development stages. Although, a greater proportion of mature male than female was detected during the study, the sex ratio showed that the overall number of female was higher than male. The ovaries had multiple oocyte size classes at every stage of gonadal development, thus R. tawarensis can be classified as a group synchronous spawner or a fractional multiple spawner. CONCLUSION: The spawning seasons of R. tawarensis were three times a year and September being the peak of the reproductive season and the female was the predominant sex. This species is classified as a group synchronous spawner.

Influence of cryoprotectants on abnormality and motility of baung (Mystus nemurus) spermatozoa after long-term cryopreservation.

Study on the effect of cryoprotectants on abnormality and motility of baung, Mystus nemurus spermatozoa were evaluated using transmission and scanning electron microscopy. Four cryoprotectants, dmso, ethanol, methanol and glycerol at concentration of 10% were tested in triplicates. Three ml of fresh sperm which was diluted with 60 ml of ringer solution was added to each of twelve 5-ml vials containing of 0.50-ml of the cryoprotectants. The vials were placed in an icebox containing dry ice 5 min and then storage into container containing liquid nitrogen for 13 months. The effect of cryoprotectants on the spermatozoa abnormality and motility were significant (P<0.05). The spermatozoa abnormality was significantly lower in methanol (62.65%) compared with the other cryoprotectants. The spermatozoa motility was higher in methanol, but not significantly different with ethanol (P>0.05). It is a negative correlation between sperm motility and abnormality. Generally, higher abnormalities of spermatozoa resulted low motility.

Preliminary study on the cryopreservation of tropical bagrid catfish (Mystus nemurus) spermatozoa; the effect of extender and cryoprotectant on the motility after short-term storage.

The effects of different extenders, and cryoprotectants on the motility of tropical bagrid catfish (Mystus nemurus) spermatozoa were evaluated after short-term storage. Three extenders, physiological saline, Ringer or saline at three levels of sperm to extender dilutions (1:20, 1:30, or 1:40) and four cryoprotectants (DMSO, ethanol, glycerol or methanol) at three concentrations (5, 10, or 15%) were examined in two separate experiments. In the first experiment, milt was suspended in the respective extender at the three milt to extender dilution ratios in two sets of tubes. Extended milt in the first set of tubes was stored at -4 degrees C, and motility assessed after 24h, while the second set was kept at 23 degrees C and sperm motility was assessed immediately and at 30-min intervals thereafter. Ringer retained sperm motility better than the other extenders at all dilution levels at temperatures of 23 and -4 degrees C respectively. At 23 degrees C, the sperm motility was almost completely lost after 150 min except for those in Ringer at 1:20 dilution level which still had a motility of 18% (compared to those kept at -4 degrees C for 24, which had motility from 39 to 71%, regardless of extender). In the second experiment, various cryoprotectants were added to solutions of milt (that was diluted in Ringer at 1:20 ratio and cryopreserved in liquid nitrogen for 15 days). Sperm cryopreserved in 10% methanol had the highest motility (58%) compared with those in the other cryoprotectants at all concentrations.