Akram Ismael Shehata

This study investigated the long-term effects of stocking density on biofloc quality (water quality and proximate composition), growth performance, feed utilization, and physiological responses of red tilapia ( Oreochromis sp.) reared in a biofloc technology (BFT) system at hypersaline conditions (36 ppt). A total of 2,325 fingerlings (initial body weight: 10.90 ± 0.14 g and initial total length: 7.2 ± 0.3 cm) were randomly assigned to four stocking densities (75, 150, 250, and 300 fish m ^–3 ) in triplicate and reared for 180 days in 12 concrete tanks (1 m ³ each). Increasing stocking density significantly impaired water quality, reducing dissolved oxygen while elevating total ammonia nitrogen, nitrite, and total suspended solids. Biofloc crude protein content increased significantly with stocking density, from 25.3% at 75 fish m ^–3 to 30.2% at 300 fish m ^–3 , accompanied by a significant rise in crude lipid from 4.75% to 5.79%. Growth performance and feed utilization efficiency (final weight, weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio) were significantly higher at lower densities (75–150 fish m ^–3 ), whereas total biomass yield increased with density, reaching 61.35 kg m ^–3 at 300 fish m ^–3 . High-density groups (250–300 fish m ^–3 ) exhibited physiological stress and oxidative damage, evidenced by elevated cortisol, liver enzymes (aspartate aminotransferase, alanine aminotransferase), and malondialdehyde, along with reduced innate immune parameters (IgM, lysozyme) and antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase). These findings indicate that although higher densities maximize total yield, they compromise fish health and immune competence. Based on integrated welfare and productivity metrics, stocking densities of 75–150 fish m ^–3 are recommended for sustainable production of red tilapia in hypersaline BFT systems.

The increasing demand for sustainable alternatives to in-feed antibiotics has stimulated interest in phytogenic feed additives. This study investigated the dose-dependent effects of dietary Ginkgo biloba leaf extract (GBLE: 0, 6, 12, 18, and 24 g/kg diet) in Nile tilapia during a 98-day feeding trial. A completely randomized design was used with three replicates per treatment (40 fish per hapa; initial body weight: 8.39 ± 0.14 g). Dietary GBLE supplementation improved final body weight, body weight gain, specific growth rate (SGR), and feed conversion ratio (FCR) in a dose-dependent manner, with the 18 g/kg group exhibiting superior performance ( P < 0.05). Second-order polynomial regression suggested estimated dietary levels of approximately 20.75 g/kg for maximum SGR and 16.44 g/kg for minimum FCR within the tested inclusion range. Polynomial regression identified optimal dietary levels of 20.75 g/kg for maximum SGR and 16.44 g/kg for minimum FCR. All GBLE-supplemented groups exhibited increased hemoglobin concentration, lymphocyte percentage, and total serum protein, together with lower serum cholesterol, triglycerides, and ALT activity. In addition, AST activity was reduced in fish fed the highest dietary GBLE level (24 g/kg). lysozyme activity, immunoglobulin M, and complement C3 were elevated in all GBLE groups relative to the control. Hepatic and serum antioxidant enzymes (SOD, GSH-Px) and total antioxidant capacity were increased, while malondialdehyde was markedly reduced across all supplemented groups. Intestinal amylase, lipase, and protease activities were enhanced. Representative liver sections from GBLE-supplemented fish showed well-preserved hepatocellular morphology, clearly defined sinusoidal spaces, and prominent pancreatic acini with no evidence of necrosis, inflammatory infiltration, or degenerative changes. These findings suggest that dietary GBLE at approximately 16–21 g/kg, as estimated by polynomial regression analysis under the present experimental conditions and supported by the superior responses observed in the 18 g/kg treatment group, may represent an exploratory inclusion range for Nile tilapia. However, these estimates should be validated in future practical studies before recommendation for commercial application. Within this range, the tested commercial GBLE preparation shows potential as a promising phytogenic feed additive that could contribute to reduced reliance on antibiotic growth promoters in intensive tilapia aquaculture.

This study evaluated the effects of dietary silymarin, stevioside, and their combined supplementation on the growth performance, physiological responses, immune competence, antioxidant status, and disease resistance of Nile tilapia (Oreochromis niloticus, initial body weight: 2.49 ± 0.10 g) over a 90-day feeding period. Fish were fed either a basal diet (control) or diets supplemented with silymarin (850 mg/kg), stevioside (450 mg/kg), or a combination of both (850 mg/kg silymarin and 450 mg/kg stevioside). Dietary supplementation significantly improved growth performance and feed efficiency, with the combined treatment yielding the greatest response (P < 0.05). Enhanced digestive enzyme activity and improved intestinal and hepatic structure were observed in supplemented groups. Blood biochemical analyses revealed enhanced protein status and reduced glucose, cortisol, and cholesterol levels without adverse effects on hepatic or renal function. Immune and antioxidant responses were enhanced, accompanied by reduced lipid peroxidation. Following Aeromonas hydrophila challenge, supplemented fish reduced cumulative mortality, particularly in the combined treatment. At the molecular level, dietary additives upregulated genes associated with growth, metabolism, immunity, and antioxidant defense. In conclusion, co-supplementation with silymarin (850 mg/kg) and stevioside (450 mg/kg) produced beneficial effects, supporting their potential as functional feed additives to enhance growth performance, health status, and disease resistance in Nile tilapia.

The intensification of aquaculture necessitates sustainable alternatives to synthetic growth promoters and antibiotics. Silybum marianum (milk thistle) has emerged as a promising phytogenic additive rich in silymarin, a flavonolignan complex with potent hepatoprotective, antioxidant, and immunomodulatory properties. This review synthesizes recent findings on the use of milk thistle in fish and crustacean diets, highlighting improvements in growth performance, hepatic function, antioxidant enzyme activity, and immune responses. Evidence indicates that silymarin stabilizes hepatocyte membranes, enhances detoxification pathways, and strengthens stress resilience, thereby reducing disease incidence and antibiotic dependence. Advances in nanoencapsulation and synergistic combinations with probiotics and selenium have further enhanced its bioavailability and efficacy. Despite encouraging outcomes, research gaps persist regarding standardized dosing, species-specific responses, long-term safety, and cost-effectiveness under farm conditions. Future studies should integrate molecular and omics approaches to clarify mechanisms and optimize formulations for commercial application. Overall, S. marianum represents a multifunctional, eco-friendly additive that supports sustainable and health-oriented aquaculture production.

Cryopreservation reduces ram sperm viability and fertilizing ability by inducing oxidative stress, membrane damage, and DNA fragmentation. This study evaluated whether adding chitosan-stabilized nano green tea extract (Nano-GTE) to a Tris-soybean lecithin extender improves post-thaw semen quality and fertility of Ossimi rams. Ejaculates (pooled from five mature rams) were extended with Tris-soybean lecithin containing 0 (control), 50, 100, 150, or 200 µg/mL Nano-GTE, equilibrated at 5 °C for 4 h, frozen in 0.25 mL straws, stored in liquid nitrogen and thawed at 37 °C for 30 s. Post-thaw progressive motility, viability and membrane integrity were significantly higher in the 100 µg/mL group (PrM: 46.3 ± 0.21% vs. control 41.5 ± 0.22%; Viability: 47.1 ± 0.27% vs. control 42.8 ± 0.24%; Membrane integrity: 47.6 ± 0.26% vs. control 43.9 ± 0.27%; P < 0.001). DNA fragmentation (Comet assay) was lowest in the 100–150 µg/mL groups (DNA damage: 5.0 ± 0.21% at 100 µg/mL vs. control 8.3 ± 0.21%; P < 0.001). Antioxidant capacity (TAC) in the post-thaw medium increased at 100 µg/mL, while markers of membrane damage (MDA, AST, ALT, LDH) were reduced compared with control ( P < 0.05). Fertility (pregnancy rate after cervical AI) was higher with semen from the 100 and 150 µg/mL groups, whereas the 200 µg/mL dose impaired some parameters. Together, these results indicate that supplementing a Tris–soybean lecithin extender with Nano-GTE at 100 µg/mL markedly improves the post-thaw quality and fertility of ram sperm; higher doses (≥ 200 µg/mL) may be detrimental.

This study evaluated the independent and combined effects of dietary coenzyme Q10 (CoQ10) and stevioside on growth metrics, physiological status, stress tolerance, antioxidant capacity, immune responses, tissue morphology, and gene expression in Oreochromis niloticus. Fish were fed one of four experimental diets for 90 days: a control diet, CoQ10-supplemented diet (40 mg/kg), stevioside-supplemented diet (450 mg/kg), or a combined diet containing both additives (40 mg/kg CoQ10 + 450 mg/kg stevioside). Dietary supplementation significantly improved growth performance, with the combined treatment yielding the highest final body weight (40.43 ± 0.59 g vs. 29.35 ± 0.49 g in control), weight gain (36.85 ± 0.66 g vs. 25.74 ± 0.54 g), specific growth rate (2.69 ± 0.07%/day vs. 2.33 ± 0.04%/day), and the minimum feed conversion ratio (1.77 ± 0.01 vs. 2.10 ± 0.03). Digestive enzyme activities were markedly enhanced, with amylase increasing from 7.41 ± 0.51 to 9.27 ± 0.15 U/mg, lipase from 2.34 ± 0.04 to 3.29 ± 0.06 U/mg, and protease from 25.64 ± 0.53 to 31.83 ± 0.25 U/mg in the combined group. Histological analyses revealed substantial improvements in intestinal villus length and liver architecture, particularly under combined supplementation. Fish receiving supplemented diets exhibited significantly enhanced antioxidant enzyme activities, with superoxide dismutase increasing from 16.47 U/mL in the control to 25.05 U/mL in the combined group, catalase from 15.52 to 21.15 U/mL, and glutathione peroxidase from 11.46 U/mL in the control to 18.76 U/mL in the combined group, while malondialdehyde decreased from 9.76 to 4.92 nmol/mL. Gene expression analysis revealed marked upregulation in the combined treatment: insulin-like growth factor 1 (17.45-fold), glucose transporter 4 (19.39-fold), interleukin-1β (5.53-fold), immunoglobulin heavy chain (11.49-fold), Interferon-1 alpha (2.09-fold), superoxide dismutase (6.99-fold), catalase (5.63-fold), and glutathione reductase (13.99-fold) compared to control. Dietary CoQ10 and stevioside significantly reduced stress-related biochemical indicators, with serum glucose decreasing from 63.3 ± 0.69 to 52.98 ± 0.70 mg/dL and cortisol from 12.29 ± 0.34 to 11.12 ± 0.18 ng/mL in the combined group. Following hypoxia challenge, the combined treatment maintained lower glucose (90.48 ± 0.86 mg/dL vs. 110.2 ± 0.8 mg/dL) and cortisol levels (29.77 ± 0.33 ng/mL vs. 34.49 ± 0.78 ng/mL) compared to control. Hypoxia tolerance was substantially improved, with median lethal time prolonged from 120 min in the control to 175 min in the supplemented groups. Overall, the combined supplementation strategy demonstrated beneficial effects across multiple physiological, biochemical, and molecular indicators, suggesting that CoQ10 and stevioside can be effectively used as nutraceutical feed additives to enhance performance, health status, and stress resilience in Nile tilapia.