Cambios morfológicos en gametos del barbo tigre Puntius tetrazona (Cypriniformes: Cyprinidae) e implementación de la fertilización in vitro

Abstract

The production of ornamental fishes represents an economic activity of a growing number of Mexican families. Nevertheless, the reproduction of fish in captivity is one of the complications faced by farmers. This study was set up to: (i) evaluate the morphological and functional changes induced by hydration in the gametes of fish tiger barb (Puntius tetrazona; 240 samples) at tree times after hydration (10, 20 and 30s) with classic spermograms (volume, sperm concentration, viability, motility, and normal morphology); and (ii) evaluate the implementation of in vitro fertilization based on the ovulation rate, the percentage of fertilization and hatching; and the larval numbers obtained after 72 hours. The average volume of milt was 3.0 ± 0.7 μL, and the minimum, maximum and average concentration of sperm was 44.4 x 10(6) spz/mL, 52.3 x 10(6) spz/mL, and 48.1 ± 5.9 x 10(6) spz/mL, respectively. The viability and motility of the sperm was 84.6 ± 3.2% and 81.5 ± 2.2%, respectively. The diameter of the sperm with/without water contact was 2.10 ± 6 μm and 3.8 ± 1.0 μm (p < 0.05); the largest diameter was recorded 30 seconds after the contact with water. For oocytes, the smaller and larger diameters were recorded at 10 and 30s, respectively (both with/without water contact); the oocytes diameters after 10 and 30 seconds of contact with water were 1.11 and 1.55 mm, respectively. A higher ovulation rate was recorded using the in vitro fertilization: 250 ± 50 oocytes versus 28 ± 09 oocytes (during natural fertilization; p < 0.05). Nevertheless, fertilization and hatching rates were higher for the natural fertilization (80 and 60%, respectively). Considering the number of larvae obtained after 72 hours, our results showed a higher value for the in vitro fertilization (75 ± 18 compared to 13.4 ± 12 of the natural fertilization; p < 0.05). We propose this fish as a model for other ornamental fishes of commercial interest. Our results demonstrate that the in vitro fertilization is a very high viable option to optimize and maximize resources; besides, the reproduction management optimization under controlled conditions may enhance wild fish stocks preservation.