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Fish meal (FM) remains an essential protein source with certain limitations like cost and sustainability in the aquaculture industry. Underutilized agricultural wastes with nutraceutical potential could be the feasible solution. This study paved the way for new avenues in the form of economically sustainable low-cost feed for betterment of aquaculture, by evaluating watermelon rind (WMR) as fish meal replacement in diets for Labeo rohita(rohu). Dried water melon rind was incorporated into five isonitrogenous diets (control, 25% fish meal replacement (FMR), 50% FMR, 75% FMR, and 100% FMR then fed to triplicates groups of L. rohitafingerlings. The experiment was conducted for 60 days. There were significant (p<0.05) improvements in nutritional indices of fish fed with 50% FMR. The digestive enzyme analysis showed a promising result in fish fed with 50% FMR diet compared to the control and other experimental diets indicating that fishmeal replaced with 50% FMR diet will be suitable for the digestion in the experimental fish rohu. Finally, histological alterations of organs showed a reduction in the damage of tissues in fish fed with WMR inclusion diets. Enrichment of amino acids (AA) and fatty acids (FA) was observed in the fish muscle. Overall, our results confirm that the 50% fishmeal replacement diet with watermelon rind is a promising alternative for fish meal displaying no adverse effects. Thus, the study concludes that the partial replacement of fishmeal by WMR provides new insights into nutrient utilization, and growth performances, digestibility, and biochemical compositions of freshwater fish L. rohita.

Recently, researchers in aquaculture become interested in green synthesized nanomaterials as a superior alternative to current conventional methodologies. The present work shows that Moringa oleiferasynthesized magnetite nanoparticles (MS-Fe3O4NPs) might offer a possible substitute for common antibiotics to treat Aeromonas sobriainfection in African catfish (Clarias gariepinus). MS-Fe3O4NPs demonstrated an in vitroantibacterial potential (21 mm inhibition zone) against A. sobria. The fish (n = 120; average body weight: 90 ± 3.5 g) were randomized into four groups (control, MS-Fe3O4NPs, A. sobria, and MS-Fe3O4NPs + A. sobria), where 1.2 mg/L of MS-Fe3O4NPs was used as bath treatment for seven-days. A. sobriainfection caused substantial elevations in malondialdehyde, tumor necrosis factor-alpha, stress indices, and hepato-renal biomarkers as well as a lower survival rate. Moreover, an apparent depletion in the level of antioxidants, the protein profile, and immune indicators were the consequences of A. sobriainfection. Surprisingly, treatment of A. sobria-infected fish with MS-Fe3O4NPs recovered these parameters. Hence, MS-Fe3O4NPs as a water additive show promise as an antibacterial treatment against A. sobriain fish.

This study investigated the effect of using a natural dietary supplement of Crataegus Sinaica(CS) to mitigate the negative impacts of waterborne acrylamide (ACR) on the health and performance of freshwater fish, African catfish (Clarias gariepinus).For this aim, 270 fish were divided into six groups (45 fish/group). Three groups were kept in non-contaminated water and fed a non-fortified basal diet, 1% CS, and 2% CS. The other three groups were exposed to ACR (26.6 mg/L water) and fed a basal diet, 1% CS, and 2% CS. After 60 days, the growth performance, liver and kidney function, stress indicators, oxidative stress indices, immunological response, vital tissue architecture, and resistance to Aeromonas sobriahave been evaluated. Results indicated that CS dietary supplementation (1% and 2% CS) significantly counteracted ACR-induced reduced growth and survival. Furthermore, both CS dietary supplementation significantly balanced the ACR-induced leukopenia, anemia, hypoalbuminemia, hypoglobulinemia, and hypoproteinemia. Likewise, 1% and 2% CS addition to the ACR-exposed fish diets significantly reduced the ACR-induced increase in serum enzymes, bilirubin, renal damage products, hyperglycemia, and cortisol. Instead, the ACR-evoked depletion of antioxidant (glutathione peroxidase, superoxide dismutase, catalase, and reduced glutathione) and innate immune (lysozyme, complement3, and nitric oxide) components were significantly restored by both CS dietary supplementation. Besides, the ACR-induced pathological alterations in hepatic, renal, and splenic tissues were considerably lessened by CS. Besides, the reduced disease resistance of ACR-exposed fish was restored when challenged with A.sobriain a fish-fed 1% and 2% CS-fortified diet. Noteworthy, the inclusion of 2% CS produced better results than 1%. Overall, feeding C. gariepinusa diet supplemented with 2% CS significantly improved the fish's overall health, growth, and disease resistance, despite the ACR water pollution that consequently would sustain aquaculture.

High feed prices and limited access to feed are two critical problems faced by fish producers. One approach that farmers may consider is using less expensive and locally available components. We conducted a 60-day feeding trial to investigate the consequences of the dietary addition of Hemicell® (HC) as exogenous β-mannanase and lavender flower meal (LFM) in low- protein diet (25 % CP) in Oreochromis niloticus. The investigation assessed growth, feed utilization, somatic, body composition and hemato-biochemical indices, and digestive enzyme activity. Fish (N = 180; average weight: 17.17 ± 0.72 g) were haphazardly organized into six groups in triplicates (10 fish/replicate) and stocked in 18 plastic tanks (60 L). For 60-days, fish groups were fed on six prepared experimental diets. The negative control group (NCG) and positive control group (PCG) were fed basal diets containing 30 % CP and 25 % CP, respectively. Groups (G1-G4) were fed on basal diets containing 25 % CP and supplemented with 0.25 g/kg HC, 0.5 g/kg HC, 0.25 g/kg HC+ 10 g/kg LFM, and 0.5 g/kg HC+ 10 g/kg LFM, respectively. The findings showed decreases in the growth, body composition (crude protein and lipids), and white blood cells count (WBCs) in PCG as compared with the control group (NCG); meanwhile, no significant alteration was recorded for other parameters. Dietary addition of HC alone or with LFM enhanced growth, feed utilization, digestive enzymes activity (trypsin, amylase, and lipase), serum total protein, and hematological indices (red blood cells count, WBCs, and Hb) as compared with PCG. The highest results were notable in G2. No marked impacts were observed on water quality parameters, fish survival, somatic index (hepato-somatic and visceral-somatic), and the level of cholesterol, glucose, and creatinine in fish serum by dietary HC or LFM. However, values of triglycerides, urea, hepatic enzymes (alanine and aminotransferases), and body crude lipids increased by supplementation of HC alone or with LFM. Our findings demonstrated that feeding O. niloticusa low-protein diet supplemented with HC (0.5 g/kg) could promote growth, digestive capability, and health status. This provides a platform for potential exogenous enzyme (HC) use in low-protein diets to reduce feed costs and support the aquaculture industry.

Copper oxide nanoparticles (CuONPs) have attracted much interest due to their catalytic and anti-bacterial activity. The present study exhibits that Moringa oleiferasynthesized CuONPs (MS-CuONPs) might provide a promising anti-bacterial substitute for conventional antibiotics to treat Staphylococcus aureusinfection in African catfish. MS-CuONPs showed an in vitroanti-bacterial activity (21.33±0.80mm inhibition zone) against S. aureus. One hundred-twenty fish (average weight: 120±5.36g) were haphazardly allocated into four groups in triplicates for 10 days (control, MS-CuONPs, S. aureus, and MS-CuONPs + S. aureus), where a concentration of 0.1mg/L of MS-CuONPs was used. The S. aureusinfection induced a marked reduction in immunological (lysozyme, complement 3, and nitric oxide), protein profile (total protein, total globulins, and albumin), and hepatic antioxidant (total antioxidant capacity, superoxide dismutase, and glutathione peroxidase) indices as well as a higher mortality rate (46.67%). Moreover, an apparent elevation in the values of tumor necrosis factor-alpha (TNF-α), hepatic malondialdehyde (MDA), stress biomarkers (cortisol and glucose), and hepato-renal indicators (aspartate aminotransferase, alkaline phosphatase, alanine aminotransferase, creatinine, and urea) were the consequences of S. aureusinfection. Interestingly, treatment of S. aureus-infected fish with MS-CuONPs improved these parameters. According to these outcomes, MS-CuONPs as a water additive can protect fish against the negative impacts of S. aureusand can be used a promise anti-bacterial agent.

Our study proposed a promising anti-fungal therapy to control Saprolegnia spp.infection in Nile tilapia (Oreochromis niloticus). A Moringa oleiferasynthesized silver nanoparticles (MS-AgNPs) showed an in vitroanti-fungal activity against Saprolegnia spp.with an inhibition zone of 18 mm. A total of 220 O. niloticus(45 ± 0.56 g) were used in this study. A preliminary investigation was conducted by using 100 fish for determining the safe dose of MS-AgNPs which was found to be 0.6 mg/L. Another 120 fish were divided into four groups; the first (control) and second groups (G1and G2) were non-infected and exposed to 0 and 0.6 mg/L MS-AgNPs, respectively. The third and fourth groups (G3and G4) were infected with Saprolegnia spp.(1.5 × 104spores/L) and exposed to 0 and 0.6 mg/L MS-AgNPs, respectively. The experiment lasted for 7 days. The infection with Saprolegnia spp.induced immunosuppression expressed by a marked decrease in immunoglobulin M, nitric oxide, complement 3, and lysozyme activity, with a 41 % survival rate. Additionally, a marked decline in the values of hepatic and branchial antioxidant enzymes (superoxide dismutase and catalase) in addition to serum total antioxidant capacity and protein profile indices. In contrast, Saprolegnia spp.infection elevated hepatic and branchial malondialdehyde, hepatic function indicators, and stress biomarkers (cholesterol and triglyceride) with up-regulation of the pro-inflammatory cytokines (IL-1ßand TNF-α), and the anti-inflammatory cytokines (IL-10and TGF-β). Histopathological findings of the gills and musculature of infected fish showed severe hyperplasia of the epithelial lining with a fusion of secondary lamellae and necrotic myocytes admixed with edema. Interestingly, treatment of the challenged fish with MS-AgNPs at a dose of 0.6 mg/L could improve these variables by enhancing the histological architecture. According to these findings, MS-AgNPs have an ameliorative effect against the harmful effects of Saprolegnia spp.infection on immune-antioxidant status and hepatic functions indices. Consequently, MS-AgNPs at a dose of 0.6 mg/L is a promising option for use in the control of Saprolegnia spp.infection in aquaculture.

Mycotoxicosis is a severe challenge in the aquafeed industry and is involved in low productivity and high economic loss. On this occasion, available dietary supplements, including probiotics, may relieve the impacts of mycotoxicosis on the performances of aquatic animals. In this study, four test diets were prepared to test the effects of Bacillus subtilis(BS), ochratoxin A (OTA), and their mixture (BS/OTA) on the performances of Mullet (Liza ramada). Fish of similar initial weight (11.38 ± 0.24 g) were divided into four groups stocked in triplicate hapas (0.5 ×0.5 ×1 m) at 15 fish per hapa. Fish fed the control diet (without BS or OTA), BS (2 × 106CFU/g), OTA (1 mg/kg) or BS (2 × 106CFU/g) and OTA (1 mg/kg) (BS/OTA). After eight weeks, the final weight (FBW) and specific growth rate (SGR) were markedly enhanced by dietary BS and reduced by OTA contamination, while the feed conversion ratio (FCR) was meaningfully reduced by dietary BS and increased by OTA. The hemoglobin (Hb), packed cell volume (PCV), red blood cells (RBCs), and white blood cells (WBCs) were markedly lowered by OTA toxicity. Fish fed BS, or BS/OTA diets showed no significant differences with the control in terms of Hb, PCV, RBCs, and WBCs (p˃ 0.05). The BS-fed fish showed the same normal intestinal and liver structure with an improved appearance of intestinal villi. The OTA-exposed fish showed deterioration of intestinal mucosa and stunted growth of intestinal villi with severe liver vascular dilatation and congestion in addition to hepatocytes degeneration. The combination of BS with OTA alleviated the pathological effect of individual OTA on the intestinal villi, improved intestinal morphology, and restored the normal hepatic structures with mild periductal inflammatory reaction around the bile duct. The blood total protein and albumin levels were markedly increased by dietary BS and lowered by OTA. Fish fed BS/OTA diet had higher alanine aminotransferase (ALT), aspartate aminotransferase (AST), and urea than fish fed the control but lower than those contaminated with OTA. The catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were markedly increased by dietary BS and lowered by OTA toxicity. However, the malondialdehyde (MDA) level was decreased by dietary BS and increased by OTA toxicity. Interestingly, fish fed the control and BS/OTA diet had similar FBW, SGR, FCR, survival rates, Hb, PCV, RBCs, WBCs, creatinine, CAT, GPx, SOD, and MDA levels. In conclusion, dietary B. subtilisrelieved the negative impacts of OTA contamination via protecting fish's intestine, liver, and kidney function.