Conditioning, assessment of commercial diets for captive growth of juveniles of grouper Mycteroperca xenarcha Jordan, 1888. Tumbes, Peru

Se evaluó el acondicionamiento al cautiverio y el crecimiento de juveniles de Mycteroperca xenarcha empleando dietas comerciales. Durante 14 meses (5 meses de acondicionamiento y 9 de crecimiento) se trabajó con 105 ejemplares de tallas homogéneas, distribuidos en cuatro grupos de tratamiento: T1 (pellet 50%) T2 (pellet 40%) T3 (pellet 50%+alimento fresco) y T0 (alimento fresco). Mensualmente se registró longitud total (Lt) y peso total (Pt). Se determinó el incremento diario de peso individual (IDPI), la tasa de crecimiento específica, factor de condición, factor de conversión alimenticia y supervivencia de cada tratamiento. Estadísticamente se fijaron dos grupos en términos de Lt: T1-T2 y T3-T0 (ANOVA, F=4,272; p = 0,012, Tukey p = 0,236 y p = 0,694), registrándose mejores valores de crecimiento en T3 (22,50 mm) y T0 (29,34 mm). Los mejores resultados en IDPI se obtuvieron en T3 (0,28 g/día) y T0 (0,31 g/día). Con relación al incremento en peso, los tratamientos no evidenciaron diferencias significativas (ANOVA, F = 0,403, p = 0,752). El factor de condición K mostró diferencia significativa entre tratamientos (ANOVA, F = 31,05; p < 0,05), verificándose dos grupos: T1–T2 y T3–T0 (Tukey p = 0,994 y p = 0,422). Estos resultados indican que para garantizar el crecimiento de M. xenarcha en condiciones de cautiverio se debe incluir alimento fresco en la dieta, sugiriendo que los alimentos formulados no cumplen por sí solos con los requerimientos nutricionales de la especie. Palabras clave: Mycteroperca xenarcha, mero, pellet, crecimiento en cautiverio ABSTRACT: The captive conditioning and growth of juveniles of Mycteroperca xenarcha were assessed by using commercial diets. Over a 14-month period (5 months of conditioning and 9 months of growth) we worked with 105 specimens of homogeneous sizes, which were distributed in four treatment groups: T1 (pellet 50%) T2 (pellet 40%) T3 (pellet 50% + fresh food) and T0 (fresh food). Total length (TL) and total weight (TW) were recorded monthly. Individual daily weight increase (IDWI), specific growth rate, condition factor, feed conversion factor and survival of each treatment were determined. Statistically, two groups were fixed in terms of TL: T1-T2 and T3-T0 (ANOVA, F=4.272, p = 0.012, Tukey p = 0.236 and p = 0.694), by recording better growth values in T3 (22.50 mm) and T0 (29.34 mm). The best results in IDWI were obtained in T3 (0.28 g/day) and T0 (0.31 g/day). Regarding the increase in weight, the treatments did not show significant differences (ANOVA, F = 0.403, p = 0.752). The (K) condition factor showed a significant difference between treatments (ANOVA, F = 31.05, p < 0.05), with two groups: T1-T2 and T3-T0 (Tukey p = 0.994 and p = 0.422). These results suggest that to ensure the growth of M. xenarcha under captive conditions, fresh food should be included in the diet and it is strongly implied that the formulated foods do not, by themselves, meet the nutritional requirements of the species. Keywords: Mycteroperca xenarcha, mero pellet, growth in captivity