[Ultrastructure and sperm cryopreservation of the amazon catfish (Leiarius marmoratus) in captivity]

ABSTRACT The aims of this study were to describe the spermatozoon ultrastructure and to evaluate the sperm cryopreservation of the amazon catfish with three cryoprotectant agents (10% methanol, 10% DMSO, and 10% ethylene glycol) and two activator agents (0.29% NaCl and 1% NaHCO3). Glucose 5% extender was used as a diluent solution and sperm loaded in 0.25 straws was frozen in nitrogen vapor (dry shipper). Fresh spermatozoon was 25.46±2.54μm long, the head was spherical (1.51±0.18μm) with no acrosome, the midpiece was cone shaped (0.93±0.17μm) with presence of vesicles, slightly asymmetric, and the flagellum was single (21.48±2.45μm). Post-thawed semen presented higher values (P< 0.05) for duration, vigor and sperm motility rate with cryoprotectants 10% methanol and 10% DMSO. The duration of sperm motility was longer (P< 0,05) when triggered in 1% NaHCO3 (96-21 s). Leiarius marmoratus semen cryopreserved with DMSO and methanol, presented respectively 7.32±4.21% and 8.94±6.69% of motility. However, the results were not satisfactory to establish a protocol for the specie.