Effect of stocking density on growth and survival of fine flounder Paralichthys adspersus (Steindachner, 1867) larvae
ABSTRACT Larviculture is a critical stage during the production of marine fish species and it is related to highest mortalities. The production of juveniles depends on a successful larval rearing, consequently the importance to investigate all aspects related to this culture stage, such as the stocking-density which is the extreme importance to improve culture conditions and reduce stress and mortality. Therefore, the objective of this study was to evaluate the effect of three stocking densities (10, 20 and 30 larvae L-1) on growth and survival of the fine flounder larvae, an important commercial species, under laboratory conditions. The number of larvae for each treatment was distributed randomly in 12-141 L fiberglass-tanks in a static-batch system. We used one day post-hatching larvae (DPH) and first feeding began two DPH with enriched rotifers (0.5 to 4 rotifers mL-1). The standard length (mm) was determined at 1, 5, 10 and 20 DPH, and the dry weight (mg) at the beginning and end of the experimental trial. Besides, the specific growth rate (SGR) and the coefficient of variation (CV) were calculated. Our results exposed that the stocking density of 10 larvae L-1 had significantly higher growth (8.14 mm and 0.90 mg), SGR (20.71 ± 1.48% d-1) and survival (42.38%) compared to the 20 and 30 larvae L-1 stocking densities. Additionally, treatment stocked with 10 larvae L-1 resulted in the highest final weight (0.90 ± 0.25 mg) and the lowest variation in sizes (CV = 5.86 ± 1.56). In conclusion, there is a significant effect of the stocking density on the growth and survival during the larval rearing of P. adspersus, and according to the results obtained in this study, the best stocking density for this species was that of 10 larvae L-1. More research is necessary to evaluate other parameters to improve growth and survival during the larval rearing of this species.