Currently, it has been given a special attention to developing technologies for short-term storage of fish semen, for a few days to weeks, using extenders of semen that do not activate the sperm motility. The short-term storage technique is indicated for fish culture to facilitate the artificial reproduction and to increase its efficiency. The objective of this study was to verify the effect of BTS (Beltsville Thawing Solution - MINITUB®) as an extender for pacu (Piaractus mesopotamicus) semen. Semen of each of the six males (previously treated with carp pituitary extract) was divided into three fractions: one fraction was kept in natura and the other two fractions were diluited (1:3) with either extender 1 (BTS 5% + potassium iodide 0,16%) or extender 2 (BTS 5% + sodium citrate 1,28%). The sperm motility was induced with distilled water, and the percentage and duration of sperm motility was scored. The percentage of moving sperm cell was significantly higher (P<0,05) in semen in natura (95,00 ± 3,16%) compared with semen diluted in extender 1 (80,00 ± 9,49%) or 2 (80,00 ± 11,40%). On the other hand, the duration of sperm motility was not affected by any extender (P>0,05) and ranged from 221,50 ± 207,89 seconds (semen diluted in extender 1) to 486,83 ± 314,55 seconds (semen in natura). After that samples for the evaluation of the sperm concentration were collected, with an average value of about 13,89 ± 1,26 x 10(9)/mL. One can conclude, that BTS may be used to preserve pacu semen, as long as the salts used may be added on a higher concentration, in order to increase the BTS solution osmolarity. It is also suggested that other salts should be tested.
Extenders; sperm motility; reproduction