Motility data (velocity and linearity, sample videos of microcapillary chemotactic test) of rainbow trout, common carp and sterlet spermatozoa in the presence of ovarian fluid

Spawning behaviour and reproductive strategies of various fish species exhibit remarkable adaptability, enabling them to effectively leverage sperm competition and selection mechanisms within their distinct environmental conditions. This study compares the impact of ovarian fluid (OF) on fertilisation performance in three taxonomically distant freshwater fish species: rainbow trout, sterlet, and common carp. These species, characterised by diverse spawning behaviours, exhibit variations in OF attributes, influencing gamete performance and <i>in vitro</i> fertilisation outcomes. Rainbow trout, spawning in streams, release eggs into an OF-rich cloud, promoting enhanced motility and prolonged movement of spermatozoa. Sterlet deposits eggs in multiple batches enveloped in OF, temporarily restraining spermatozoa’s motility. This delay mechanism may hold sperm cells from one or more males until OF dilution restores motility. Common carp spermatozoa show high sensitivity to OF, shifting from linear to exploratory motion in the presence of even low OF concentrations, which is beneficial for spawning scenarios in shallow waters involving active mixing of gametes by parent bodies<i>. In vitro</i> fertilisation assays supported these suppositions. The findings highlight the significant OF influence on male gamete performance, aligning with species-specific spawning behaviours and offering insights into the interplay between reproductive strategies and the gamete encounter microenvironment in external fertilisers.The files contain data on curvilinear velocity (VCL, um/s) and path linearity (LIN) of common cart, rainbow trout and sterlet spermatozoa in aqueous solutions of ovarian fluid from respective species. Motility parameters were evaluated in media with varying concentrations of ovarian fluid (100%, 50%, 25%, 10%, and 0%). The files contain sample videorecords of the chemotactic microcapillary test conducted to assess the response of spermatozoa to the injection of ovarian fluid or egg water into the activating medium using glass microcapillaries. This method represents an accumulation assay conventionally applied for simple spermatozoa chemotaxis analysis. For detailed methods, please refer to the accompanying manuscript.