The aim of this study was to compare the organismal responses of farmed and wild-caught turbot, Scophthalmus maximus, based on analyses of biochemical plasma parameters, leukocyte profile, and histological tissue profile of gills, kidney, liver, intestine, and spleen, as well as gene expression of stress proteins in kidney and liver tissue. The results revealed significant differences in plasma triglycerides (TRIG), total protein (TP), albumin (ALB), globulin (GLOB), bilirubin (TBIL), creatinine (CRE) levels, creatine kinase (CK), and superoxide dismutase (SOD) activities that were higher, and A/G ratio, calcium (Ca) and phosphorus (P) concentrations, alkaline phosphatase (ALP), and glutathione peroxidase (GPx) activity, which were lower in farmed population. The neutrophil-leukocyte (N:L) ratio and gene expression of HSP70, HSP90, and WAP65-2 were increased in the wild-caught turbot. The wild-caught turbot were infested with the gill digenean parasite Dactylogyrus sp. and tapeworm Bothriocephalus scorpii. The obtained results provide valuable data for the assessment of the physiological responses of turbot for future comparative studies of the effects of various endogenous and exogenous factors on homeostasis of this species.

The aim of the study was to evaluate the growth, fatty acid profile and concentration of malondialdehyde of muscle tissue of meagre Argyrosomus regius fed diets with different lipid content. The long-term experiment was conducted in three feeding groups: A (CP = 52.0; CL = 21.0), B (CP = 56.0; CL = 18.0), C (CP = 48.0; CL = 16.0) with two replicates in marine net cages on Bisage Island, Adriatic Sea over 20 months. At the beginning of the experiment, fish were of equal weight (6.83 ± 1.03 g) and length (8.57 ± 0.49 cm) and were fed to satiation during the experiment. At the end of the experiment, the fish from each feeding group (n = 110) were measured and muscle tissue was collected (n = 60) and stored at −80 °C until analysis. The final weight and condition factor were significantly different (p < 0.05) between the groups. The highest ratio of crude fats and n-3/n-6-fatty acids was found in the muscle tissue of group A. Fish fed diet A also exhibited higher MDA levels compared to fish in the other feeding groups, indicating elevated levels of lipid peroxidation in muscle tissues. Experimental feeding group A showed better growth performance, a higher content of the beneficial fatty acids EPA and DHA and a more favorable n-3/n-6 ratio than feeding groups B and C. Continuously monitoring and adjusting feeding protocols in accordance with lipid content and fatty acid composition could maximize growth and health outcomes in meagre farming.

The gilthead seabream (Sparus aurata) is cultured throughout the Mediterranean; the sea temperature most significantly determines the duration of farming. Sea temperatures reduce gilthead seabream’s need for feed and fish growth is not expected in these conditions. It is hypothesized that improving feed formulation could improve growth during the winter months. For the research, two groups were formed, and fed for a month with two types of fish feed of different nutritional composition at an average temperature of 13.9 ± 0.90 °C. The fish from cage A (21.53 ± 1.53 cm; 173.77 ± 38.24 g) were fed fish feed containing protein and lipid 100% from marine origin (H1). The fish from cage B (22.17 ± 1.43 cm; 181.08 ± 43.05 g) were fed with commercial feed for gilthead seabream, whose proteins and lipids were partially replaced by plant raw materials (H2). The temperature was measured daily and samples were taken at the beginning and end of the experiment for biometrics, which included the fish’s total length, total weight, and condition factor. This study showed that fish fed with a modified formula achieved higher growth parameters than fish fed with commercial feed. The data obtained indicate that gilthead seabream can grow at low temperatures and there is a need for further research to ensure the correct selection of raw materials for the testing and production of feed for the period of low sea temperatures.