Sperm production of Steidachneridion parahybae (Steindachner 1877) and the effect of hormonal induction throughout one reproductive cycle

The present study assessed the semen production and spermatozoa characteristics of Steidachneridion parahybae throughout one reproductive cycle in captivity and the effect of the induction of maturity with carp pituitary extract (CPE). Hence, six semen samples were collected from 26 specimens of S. parahybae. The samples were divided into two groups (non-induced and induced) and tested between October 2009 and April 2010 (water temperature = 21.85 ± 0.77 and 21.85 ± 0.80°C, respectively, and density 705 and 679 g m−2 for non-induced and induced groups, respectively). The effects of hormonal induction on the studied seminal parameters were not significant (P > 0.05). The mean values and standard error obtained for induced and non-induced specimens were respectively: relative volume of semen (9.39 ± 1.19 and 9.87 ± 1.03 ml kg−1); sperm motility rate (79.05 ± 1.85 and 81.77 ± 1.54%); motility duration (38.76 ± 0.74 and 39.94 ± 0.80 s); sperm concentration (9.24 ± 0.88 and 8.75 × 109 ± 0.58 × 109 sptz ml−1); pH of the seminal plasma (7.23 ± 0.06 and 7.32 ± 0.05), and osmolality of the seminal plasma (263.21 ± 2.40 and 259.46 ± 3.54 mOsm kg−1). The results indicated that this species presents continuous but variable sperm production, and that hormonal induction does not significantly improve the sperm characteristics of the species.