The study evaluated the nutritional quality and investigated the heavy metals concentration in muscle tissues of five commercially important marine fish species, including brownspotted grouper (Epinephelus chlorostigma), squaretail coralgrouper (Plectropomus areolatus), black pomfret (Parastromateus niger), goldbanded jobfish (Pristipomoides multidens), and blueskin seabream (Polysteganus coeruleopunctatus) from the Red Sea, Jeddah Coast, Saudi Arabia. Significant differences (p < 0.05) were observed in the proximate chemical composition of fish muscles in these species. The highest protein content (17.66 ± 0.58%) was achieved in blueskin seabream while the lowest (15.28 ± 0.46%) was observed in brownspotted grouper. The highest lipid content (2.97 ± 0.45%) was recorded in squaretail coralgrouper while the lowest (1.52 ± 0.26%) was observed in blueskin seabream. Heavy metal concentrations varied significantly within and between fish species under study (p < 0.05). Significant differences in the concentration of heavy metals among fish species were recorded. Results revealed that the bioaccumulation of Cr, Fe, Ni, and Cd in muscles of fish species under study was higher than the standard concentration, but that of Mn, Cu, and Pb were less than the standard concentration recommended in the EU, FAO, and WHO guidelines. In conclusion, these fish species represent a high-quality food source but is unsafe due to the level of certain minerals in their tissues. Results also indicated that the Red Sea environment is contaminated with heavy metals, which was reflected in the tissues of fishes used in this study.

Marine-derived substances are known for their beneficial influences on aquatic animals’ performances and are recommended to improve intestinal health, immunity, and anti-oxidative status. The present study investigates the role of chitosan nanoparticles on the intestinal histo-morphometrical features in association with the health and immune response of Grey Mullet (Liza ramada). Chitosan nanoparticles are included in the diets at 0, 0.5, 1, and 2 g/kg and introduced to fish in a successive feeding trial for eight weeks. The final body weight (FBW), weight gain (WG), and specific growth rate (SGR) parameters are significantly increased while feed conversion ratio (FCR) decreases by chitosan nanoparticles compared to the control (p < 0.05). The morphometric analysis of the intestines reveals a significant improvement in villus height, villus width, and the number of goblet cells in chitosan-treated groups in a dose-dependent manner. Additionally, there is a positive correlation between the thickness of the enterocyte brush border and the chitosan dose, referring to an increasing absorptive activity. Histologically, the intestinal wall of Grey Mullet consists of four layers; mucosa, sub-mucosa, tunica muscularis (muscular layers), and serosa. The histological examination of the L. ramada intestine shows a normal histo-morphology. The epithelial layer of intestinal mucosa is thrown into elongated finger-like projections, the intestinal villi. The values of hemoglobin, hematocrit, red blood cells (RBCs), total protein (TP), albumin, and globulin are significantly increased in fish fed 1, and 2 g/kg of chitosan nanoparticles compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest levels of TP and albumin are observed in fish fed 1 g/kg diet (p < 0.05). The lysozyme activity and phagocytic index are significantly enhanced by feeding chitosan nanoparticles at 0.5, 1, and 2 g/kg, whereas the phagocytic activity is improved in fish fed 1 and 2 g/kg (p < 0.05). The highest lysozyme activity and phagocytic index are observed in fish fed 1 g/kg. SOD is significantly activated by feeding chitosan nanoparticles at 1 g/kg. Simultaneously, glutathione peroxidase (GPx) and catalase (CAT) activities also are enhanced by feeding chitosan at 1 and 2 g/kg, compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest GPx and CAT activities are observed in fish fed 1 g/kg (p < 0.05). Conversely, the malondialdehyde (MDA) levels are decreased by feeding chitosan at 1 and 2 g/kg, with the lowest being in fish fed 1 g/kg (p < 0.05). To summarize, the results elucidate that L. ramada fed dietary chitosan nanoparticles have a marked growth rate, immune response, and anti-oxidative response. These improvements are attributed to the potential role of chitosan nanoparticles in enhancing intestinal histo-morphometry and intestinal health. These results soundly support the possibility of using chitosan nanoparticles at 1–2 g/kg as a feasible functional supplement for aquatic animals.

The aim of this study was to evaluate the use of dried marine seaweed, Gracilaria arcuata for the first time as dietary ingredient in partial substitution of fishmeal on the growth performance, feed utilization and body composition of African catfish, Clarias gariepinus. Four experimental diets were formulated: D1 as a control group; D2; D3 and D4 which included 10%, 20% and 30% G. arcuata meal respectively. One hundred and eighty African catfish weighing 9.62 ± 0.42 g, (mean ± SE) was divided into four groups corresponding to the different feeding regimes. The final body weight of the fishes showed significant differences (P < 0.05) between the control (D1); D2 and other treated groups D3 and D4, with weights of 66.98, 59.60, 47.34 and 30.73 g recorded for D1, D2, D3 and D4, respectively. Significant differences (P < 0.05) were also evident in weight gain, specific growth rate, and feed utilization between treatment and control groups. However, no significant differences (P > 0.05) were observed between the control group and fishes fed D2 for all previous parameters. Protein productive value, protein efficiency ratio, daily dry feed intake and total feed intake were also significantly lower in fish fed with a diet containing G. arcuata than in the control group and D2 which contains 10% of G. arcuata. Overall, the results of the experiment revealed that African catfish fed a diet with G. arcuata included in 20% and 30% levels showed poorer growth and feed utilization than the control group and D2. However, the study recommended that C. gariepinus can accept this ingredient up to 10% in their diets. More defined experiments therefore seem to be necessary in order to determine the maximum level of this marine seaweed in diets with amino acid supplementation for African catfish.

Waterborne herbicides are stressful agents that threaten the productivity and safety of finfish species. In this study, the toxicity impacts of atrazine (ATZ) and the protective role of fucoidan were investigated on the health performance of Nile tilapia. For 40 days, the total number of 180 Nile tilapia was assigned in four groups (triplicates, 15 fish/replicate), where the first (control) and third groups were offered the control diet, while the second and fourth groups were offered a fucoidan (FCN). Further, in the third and fourth groups, the water was mixed with atrazine (ATZ) at 1.39 mg/L daily. The growth rate, FCR, and survival rate were markedly enhanced by fucoidan but severely declined by ATZ exposure (p < 0.05). The morphological structure of the intestine in the control fish revealed normal structure, while fucoidan-treated groups showed eminent enhancement and branching of the intestinal villi. The intestine of ATZ-treated fish revealed deterioration and the intestinal mucosa, inflammatory cell infiltration, and separation of lining epithelium. The highest Hb, PCV, RBCs, WBCs, total protein, and albumin were observed in Nile tilapia fed fucoidan, but the worst values were seen in ATZ-intoxicated fish (p < 0.05). The liver-related enzymes (ALT and AST) and kidney function (urea and creatinine) showed impaired values by ATZ toxicity and were regulated by dietary fucoidan. Meanwhile, fish fed fucoidan and exposed to ATZ had lower total cholesterol and triglyceride values than fish exposed to ATZ without fucoidan feeding (p < 0.05). The SOD, CAT, GPx, cortisol, and glucose levels were increased in ATZ-exposed fish and reduced by fucoidan (p < 0.05). However, the level of malondialdehyde (MDA) was reduced in fucoidan-fed fish and increased in ATZ-exposed fish (p < 0.05). Altogether, dietary fucoidan is required in fish diets to alleviate the impacts of ATZ-induced toxicity.

The body composition of Nile tilapia (Oreochromis niloticus) collected from drainage canals in Al-Ahsa, Saudi Arabia and the concentration of four heavy metals; zinc (Zn), cadmium (Cd), cobalt (Co) and lead (Pb) in both fish muscles and the water collected from this environment were assessed across the four seasons. The body composition was found to change with the seasons, with the best body composition being recorded in autumn and winter, where higher levels of protein (17.24, 17.65%), and fat (0.58, 0.71%) and lower water content (80.15, 79.86%) respectively were noted. The concentration of heavy metals in both fish muscles and the water body also varied significantly with the seasons. In the fish muscles, the highest content of Zn (0.409 mg/kg dry weight) and Cd (4.140 mg/kg dry weight) was recorded in winter, however, the highest concentration of Co (0.318 mg/kg dry weight) and Pb (1.96 mg/kg dry weight) was observed in spring and summer respectively. On the other hand, the water samples collected in autumn showed the maximum concentration of Cd (1.385 mg/L), Co (0.762 mg/L) and Pb (0.18 mg/L) however, the maximum concentration of Zn (0.0041 mg/L) was recorded in winter. With the exception of Cd, the accumulation of the studied heavy metals in fish muscles was within the safe limits for seafood recommended by various organizations.

The present and future high demand of common cereals as corn and wheat encourage the development of feed processing technology that allows for the dietary inclusion of other cereals of low nutritional value in poultry feeding. Barley grains contain anti-nutritional factors that limit their dietary inclusion in the poultry industry. The treatment of barley with solid-state fermentation and exogenous enzymes (FBEs) provides a good alternative to common cereals. In this study, barley grains were subjected to solid-state microbial fermentation using Lactobacillus plantarum, Bacillus subtilis and exogenous fibrolytic enzymes. This study aimed to assess the impact of FBEs on growth, feed utilization efficiency, immune modulation, antioxidant status and the expression of intestinal barrier and nutrient transporter-related genes. One-day-old broiler chicks (Ross 308, n = 400) comprised four representative groups with ten replicates (10 chicks/replicate) and were fed corn-soybean meal basal diets with inclusions of FBEs at 0, 5, 10 and 15% for 38 days. Solid-state fermentation of barley grains with fibrolytic enzymes increased protein content, lowered crude fiber and reduced sugars compared to non-fermented barley gains. In consequence, the group fed FBEs10% had the superior feed utilization efficiency and body weight gain (increased by 4.7%) with higher levels of nutrient metabolizability, pancreatic digestive enzyme activities and low digesta viscosity. Notably, the group fed FBEs10% showed an increased villi height and a decreased crypt depth with a remarkable hyperactivity of duodenal glands. In addition, higher inclusion levels of FBEs boosted serum immune-related parameters and intestinal and breast muscle antioxidants status. Intestinal nutrient transporters encoding genes (GLUT-1, CAAT-1, LAT1 and PepT-1) and intestinal barriers encoding genes (MUC-2, JAM-2, occludin, claudins-1 and β-defensin 1) were upregulated with higher dietary FBEs levels. In conclusion, feeding on FBEs10% positively enhanced broiler chickens’ performance, feed efficiency and antioxidant status, and boosted intestinal barrier nutrient transporters encoding genes.