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

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