SEMINAL CHARACTERIZATION AND CRYOPRESERVATION OF SEMEN FROM AMAZONA JUNDIA, Leiarius marmoratus.

Developing an effective sperm cryopreservation protocol is important for the conservation and reproductive management of freshwater fish species with aquaculture and genetic potential. Leiarius marmoratus is a Neotropical catfish of growing interest for reproductive biotechnology. This study aimed to characterize the seminal parameters of L. marmoratus and evaluate the effects of two cryoprotectant solutions on sperm quality after cryopreservation. Semen was collected from five sexually mature males and evaluated for volume, sperm concentration, total motility, plasma membrane integrity, and sperm morphology. Sperm motility kinetics were assessed using computer-assisted sperm analysis (CASA). Fresh semen was subsequently cryopreserved using two treatments: T1, containing 10% methanol, 5% glucose, and 10% egg yolk; and T2, containing 10% methanol and 100 mM trehalose. Fresh semen exhibited a volume of 1.12 ± 0.40 mL, a sperm concentration of 45 × 10⁹ ± 2.58 spermatozoa mL⁻¹, and total motility of 76.47 ± 13.21%. Following thawing, total motility decreased significantly to 29.38 ± 1.62% and 37.77 ± 16.59% in T1 and T2, respectively, compared with fresh semen (P < 0.05). Cryopreservation also reduced several CASA-derived kinetic parameters, including straight-line velocity, average path velocity, linearity, straightness, wobble, and beat cross frequency, while curvilinear velocity was comparatively less affected. Plasma membrane integrity decreased from 91.40 ± 4.05% in fresh semen to 23.90 ± 4.52% and 19.60 ± 3.38% in T1 and T2, respectively. Similarly, normal sperm morphology declined after cryopreservation. No significant differences (P > 0.05) were observed between the two cryoprotectant treatments for total motility. Overall, cryopreservation significantly reduced sperm motility, membrane integrity, and morphology in L. marmoratus. While both treatments yielded limited post-thaw sperm quality, the results offer essential baseline data for optimizing cryopreservation protocols for this species and highlight its potential use in reproductive biotechnology and germplasm conservation.