QUALITATIVE SEMEN PARAMETERS AND COMPARATIVE MORPHOLOGY OF PIRAPITINGA (Piaractus brachypomus), PACU (Piaractus mesopotamicus) AND TAMBAQUI (Colossoma macropomum) SPERM

The objective of this work was to evaluate qualitative semen parameters and to compare the morphology of the sperm head among three fish species, Piaractus mesopotamicus, Piaractus brachypomus and Colossoma macropomum. The semen samples were collected from nine animals, three males per species, by the induced reproduction method in November 2011. Sperm motility was evaluated and morphology was analyzed by scanning electron microscopy. The motility rates of the three species evaluated were higher than 90%, with no difference between species. However, the duration of sperm motility was longer for pacu semen compared to the other species. The head length was 2.43 +/- 0.19, 1.94 +/- 0.07 and 2.44 +/- 0.12 mu m for pacu, pirapitinga and tambaqui sperm, respectively. The head width was 1.45 +/- 0.07,1.76 +/- 0.07 and 1.56 +/- 0.06 mu m, and the length of the intermediate piece was 1.0 +/- 0.10,1.54 +/- 0.08 and 2.07 +/- 0.33 mu m, respectively. The results show that the sperm of the three species differs in terms of external morphology (size and shape of the head) and in relation to the length of the intermediate piece.