Determinación del espermatocrito y efecto del volumen de la dosis seminante sobre la fertilidad en yamú (Brycon amazonicus)

yamú (brycon amazonicus - spix & agassiz 1829) is an omnivorous, fast- growing fish with excellent meat quality, given it commercial importance. to standardize the spermatocrit (spct), 23 samples of semen were centrifuged at 14000 g during 1, 3, 5, 7 or 10 min. the centrifugation time had a significant effect on spct value (p<0.05). with the aim to know the sperm concentration (sc) throughout the reproductive season and its relationship with the spct, 40 males were treated with carp pituitary extract (4.0 mg.kg-1). the sc was evaluated by neubauer chamber (dilution 1:1200) and spct by centrifugation at 14000 g during 5 min. the relationship between spct and sc was positive and highly significant (y= 1.69 + 0.59x; r2= 0.74; p <0.0001), but statistical differences were not observed (p>0.05) among the months evaluated (march, april and may). finally, to determine the effect of volume of seminant dose on fertility, 2 g of eggs were seminated with 3, 15,45, 90 or 180 μl of semen (n= 12). the sc was previously adjusted to contain 50000 sptz/egg, using as extender seminal plasma homologous. the fertilization rate were 83, 86, 86, 85 and 87%, respectively (p>0.05).