Replacing fishmeal with Palaemon serratus meal enhances growth, carcass traits, digestive enzymes, immune-physiological response, antioxidants, and inner organ histopathology of Dicentrarchus labrax

The aquaculture industry is currently facing significant challenges due to the increasing demand for fishmeal (FM), which is an indispensable ingredient in marine aquaculture. This study aims to reduce the reliance on fishmeal in marine fish nutrition and replace it with natural low-trophic animal sources that are more sustainable and of comparable nutritional value to those of fishmeal. Six levels of Palaemon serratus (PS) meal were tested in triplicate: 0, 10, 20, 30, 40, and 50% as a replacement for fishmeal, designated PS0, PS10, PS20, PS30, PS40, and PS50, respectively. A total of 216 apparently healthy Dicentrarchus labrax juveniles (average weight 8.75 ± 0.05 g) were randomly allocated to 18 circular fiberglass tanks. The fish were fed the experimental diet (42.75% protein) for 60 days. The results revealed a better water quality indicator (more oxygen and less ammonia) among the PS-tested treatments. The groups fed PS-supplemented diets outperformed the control group in terms of growth and feed utilization indicators, with the PS40 group performing best. A polynomial second-order regression model was employed to get the optimal results in diets which containing 42.5% PS meal for SGR and 38.5% PS for FCR. Compared with those in the PS0 group, immune-related parameters such as IgM, total protein, and total albumin increased by 18.1%, 38.5%, and 41.4%, respectively. The serum lipid profile was better in the PS30 and PS40 groups, whereas digestive enzymes were better in the PS40 and PS50 groups. PS replacement increased serum growth and immune hormone levels. Intestinal and liver histomorphology revealed that increasing the PS replacement rate enhanced sea bass health. Sea bass diets are recommended to replace 40% of fishmeal with P. serratus meal.