Understanding rigor mortis impacts on fish gamete viability

Abstract This study aimed to evaluate the viability of reproductive gametes in zebrafish ( Danio rerio ), at different rigor mortis stages. Viability assessments were conducted on oocytes at various developmental stages using LIVE/DEAD and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. For sperm evaluation, both kinetic (CASA) and morphological assessments (Rose Bengal staining) were performed. Results demonstrated that rigor mortis progression significantly impacted oocyte viability during post-rigor stages, with the following viability rates: pre- rigor (70.43 ± 12.31%), fresh/control (46.43 ± 12.54%), post-rigor (27.62 ± 22.29%), and rigor mortis (comparable to fresh/control). Conversely, sperm kinetics exhibited nuanced responses to the rigor mortis stages, with specific parameters showing sensitivity, whereas the others remained relatively stable. Sperm motility was higher in the fresh/control (63.23 ± 19.03%) and pre- rigor (58.96 ± 14.38%) compared to the post-rigor group (3.34 ± 4.65%). This study highlights the significance of the pre- rigor for successful gamete collection and preservation. These findings provide valuable insights for conservation efforts and optimization of genetic resource management for endangered fish species. This study aimed to develop effective assistive reproductive techniques by elucidating the interplay between rigor mortis and gamete quality, contributing to the broader goals of species conservation and maintenance of genetic diversity in fish populations.