Search

Heavy metals (HM) are widespread contaminants of water affecting aquatic organisms and aquatic ecosystems. Indian lotus, Nelumbo nucifera (Gaertn.), is a beneficial medicinal plant that exhibits several pharmacological properties. It is hypothesized that incorporation of Indian lotus leaf (ILL) powder may be able to alleviate toxic effects exerted by a mixture of lead (Pb), cadmium (Cd), mercury (Hg), and zinc (Zn) in Nile tilapia, Oreochromis niloticus (L.). A total of two hundred and forty fish were randomly allocated into eight groups in triplicate, in a bifactorial design (4 ILL levels × 2 HM exposures). The fish in the first four groups were fed on a basal diet (39.9% crude protein) that was enriched with 0.0, 0.1, 0.2, and 0.4% ILL (in G1–G4, respectively), with no HM exposure. In the remaining four groups, fish were fed with the same diets and, in addition, were exposed to 1/20 of the 96 h-LC50 of Pb, Cd, Hg, and Zn mixture (in G5–G8, respectively), for 45 days. The HM exposure significantly elevated the levels of serum alanine and aspartate aminotransferases, creatinine, urea, malondialdehyde, and activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). The expression level of hepatic metallothionein (MT) was up-regulated as well as high residual levels of HM in fish musculature were recorded in the HM-exposed fish. Two-way ANOVA revealed that all the studied variables were significantly affected by the ILL supplementation, HM exposure, and their interaction. Moreover, levels of MDA, CAT, SOD, and MT showed significant positive correlations with HM concentrations. Moreover, necrosis and degeneration of hepatopancreatic cells with congestion, hyperplasia, and fusion of gills lamellae were observed in HM-exposed fish. Interestingly, ILL supplementation, especially in the fish fed with 0.2 and 0.4% ILL, was observed to reduce the HM concentration in the fish body, resulting in the reduction of its toxic effects on the biochemical and antioxidant activities. These results demonstrated that dietary ILL supplementation could protect Nile tilapia against the toxic effects of HM, and therefore, may serve as a beneficial feed additive for application in the aquaculture industry.

Indiscriminate use of insecticides is a major concern due to its ubiquitous occurrence and potential toxicity to aquatic animals. This study investigated the adverse effects of lambda-cyhalothrin (LCT, C23H19ClF3NO3) and methomyl (MTM, C5H10N2O2S) on immune system modulations and growth performance of juvenile fishes. The supportive role of a taurine (TUR, C2H7NO3S)-supplemented diet was also evaluated. Juvenile O. niloticus fishes were exposed to LCT (0.079 µg/L), MTM (20.39 µg/L), or both in water and were fed on a basal diet only or taurine-supplemented basal diet. Exposure to LCT and MTM retarded growth and increased mortality rate. LCT and MTM reduced antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) and innate and humoral immunity but upregulated interleukin and chemokine expressions. Moreover, exposure to LCT and MTM elevated 8-OHdG levels and increased the mortality of Oreochromis niloticus after the experimental bacterial challenge. The TUR-enriched diet enhanced antioxidant enzymes and acted as a growth promoter and anti-inflammatory agent. TUR can modify innate and adaptive immune responses. Furthermore, TUR supplementation is a beneficial additive candidate for mitigating LCT and MTM toxicities mixed with O. niloticus aquafeed.

Recently, silver nanoparticles (AgNPs) established a prospective value in aquaculture; however, extensive use afflicts fish and environment. Therefore, the current study represents a premier report to investigate the acute exposure of African catfish, Clarias gariepinus (B.) to AgNPs and the ethological alterations in a static renewal system. Additionally, AgNPs impact on blood profile, stress, brain activity, and branchial oxidative stress parameters were evaluated. Fish (50.71 ± 3.85 g) were exposed to different concentrations (0, 6.25, 12.5, 25, 50, and 100 mg L−1) of AgNPs for 96-h without water exchange. Finney's probit analysis was used to estimate the 96-h LC50 value of AgNPs which recorded 21.38 mg L−1. In comparison to the control, the AgNPs exposed fish exhibited different ethological responses such as surfacing for gasping air, restlessness, slow swimming movement, aggressiveness, and nervousness and the scores of these behaviors and mortalities reached the high values with increasing AgNPs concentrations. There were marked reductions in hematological indices (RBCs, Hb, Hct, and WBCs), acetylcholine esterase (AChE) activity, and oxidative stress indices (superoxide dismutase (SOD), catalase (CAT), and reduced glutathione content (GSH)) of exposed groups in an AgNPs dose-dependent manner relative to the control group. On the contrary, the levels of stress-mediated indices (glucose and cortisol) and 8 hydroxy 2 deoxyguanosine (8OH2dG) were markedly decreased in all AgNPs exposed groups as compared with the control group and the reduction increased with increasing the exposure concentration. We concluded that AgNPs exposure of C. gariepinus induced marked alterations in behavior, blood profile, neurological, and branchial antioxidant parameters, and the 96-h LC50 of AgNPs was 21.38 mg L−1 and this provides a basis for future applying AgNPs as a safe therapeutic agent after considering the acute toxicity.

Significant losses in ration industry especially aquaculture resulting from aflatoxins. The effect of supplementing Nile tilapia diet with Fennel essential oil (FEO) with or without Saccharomyces cerevisiae on negative impacts of aflatoxin B1, AFB1 (200 ppb) for one month was studied. Two hundred and forty Nile tilapia of 26.6 ± 0.12 g (mean ± SE) were divided into eight groups (30 fish/group) with three replicates. G1 was fed on a basal diet only (D1), while G2 was fed on AFB1 (200 ppb) contaminated diet (D2). G3 and G4 were fed on FEO supplemented diets (1 ml/kg diet) with or without AFB1 (200 ppb) (D3 and D4), respectively. G5 and G6 were fed on S. cerevisiae supplemented diets (1 g/kg diet) with or without AFB1 (200 ppb) (D5 and D6), respectively. G7 and G8 were fed on supplemented diets with mixture from FEO (1 ml/kg diet) and S. cerevisiae (1 g/kg diet) with or without AFB1 (200 ppb) (D7 and D8), respectively. The phagocytic assay, protein profile, serum alanine aminotranferase (ALT) and creatinine were measured at the end of feeding period (30 days). The oxidative stress biomarker as catalase activity and malondialdehyde (MDA) and AFB1 residues in liver and musculature were also measured. At the end of feeding period, the phagocytic activity, total blood proteins and catalase activity showed lower significant values in AFB1 exposed fish. Also, AFB1 induced significant rising in levels of ALT, creatinine and MDA with higher residual levels recorded. Meanwhile, the aflatoxicated groups treated with FEO or S. cerevisiae or their mixture revealed significant improvement of mostly all the measured parameters. FEO can successfully relieve AFB1 noxious effects compared with S. cerevisiae in Nile tilapia. Keywords: Aflatoxin B1, Nile tilapia, Fennel essential oil, Saccharomyces cerevisiae, Phagocytic assay, Malondialdehyde

Currently, the contamination of water with different insecticides like profenofos (PFF) is a critical concern in the aquatic ecosystem. There are limited studies available on the negative impacts of PFF on common carp fish (Cyprinus carpio L.). Therefore, the existing study was designed to investigate the effect of PFF exposure (1/10 of the 96 h-LC50) on the neurobehavior, growth performance, chemical composition, oxidative status, DNA damage, apoptotic status and histological indices of the brain and gill tissues. In addition, this study seeks to detect the ability of geranium essential oil (GEO) dietary supplementation to mitigate the negative impacts of PFF. Accordingly, a total of 120 healthy fish were divided into four groups: the control group, fed on basal diet only; the other groups were fed on a basal diet supplemented with 400 mg kg-1 GEO, basal diet and PFF in water (PFF group), and supplemented diet with GEO and PFF in water (GEO + PFF), respectively, for 60 days. The results showed that PFF significantly reduced fish growth performance, crude protein, and lipid contents. It caused several behavioral alterations including spiral movement, decreased activeness, and changes in feeding behavior. Moreover, PFF increased the DNA tail length, tail moment, and the level of 8-hydroxy-2'-deoxyguanosine. Histologically, PFF induced a wide array of circulatory, inflammatory, regressive and progressive alterations in the brain and gill tissues. PFF significantly downregulated Bcl-2 and upregulated caspase-3 immuno-expression in both organs. Further, it considerably depleted the antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase. The GEO supplementation did not reach the respective control values but markedly improved most of the behavioral, physical, biochemical, oxidative, apoptotic, and inflammatory markers, altered by PFF exposure. It also protected the gill and brain tissues from the branchial and encephalopathic effects of PFF. These findings suggest that GEO dietary supplements could be advantageous for mitigating PFF negative impacts and presenting a promising feed additive for common carp in aquaculture.

The present study investigated the possible effect of profenofos (PFF) on hepato-renal functions, non specific-immunity, and oxidants/antioxidants status in common carp, Cyprinus carpio (L.), and the supportive role of geranium (Pelargonium graveolens) essential oil (GEO). A static 96-h acute toxicity test was performed to determine the 96-h LC50 of PFF in common carp fingerlings and it was found to be 47.46 μg L−1 calculated by Finney probit analysis. One hundred and twenty fish were randomly allocated into four groups in triplicate. The first served as control and second groups were fed on basal diets that were enriched with 0.0 and 400 mg kg−1 of diet GEO, respectively without PFF exposure. The third and fourth groups were fed on the same diets and in addition, were exposed to 1/10 of the 96 h-LC50 of PFF (4.74 μg L−1), respectively for 60 days. The results revealed that the PFF exposure induced marked increases in the levels of serum alanine and aspartate aminotransferases (ALT and AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine, urea, cholesterol, triglycerides (TG), and malondialdehyde (MDA). Meanwhile, the serum total protein (TP), globulins, glucose, lysozyme activity, complement3 (C3), nitric oxide (NO), and hepatic antioxidant enzyme activities as well as the reduced glutathione (GSH) content were markedly declined in the PFF-exposed fish compared to the control group. Additionally, vacuolation, pyknosis, and degeneration of hepatocytes and epithelial cells of renal tubules with mononuclear cell infiltration were observed. A strong caspase-3 and weak BCL-2 immunohisto-reactivity in the liver and kidney tissues of PFF-exposed fish were noted respective to the control. Interestingly, GEO supplementation improved these variables with nearly restoring to control values with improving the histological architecture of liver and kidney tissues. The apoptotic condition of the examined tissues was markedly restricted in the combination group than PFF-exposed group. These results concluded that GEO has ameliorative influence against toxic impacts of PFF on hepato-renal functions, immunological parameters, and oxidative stress in common carp, and therefore, maybe a valuable candidate as a dietary supplement in aquaculture.

In this study, the influence of the dietary incorporation of Echinacea purpurea (EP) extract and/or vitamin C on the intestinal histomorphology and some immunological indices were tested in the Nile tilapia (Oreochromis niloticus Linn.). O. niloticus were randomly divided into four groups. The control group G1 was fed on a basal diet, while the G2 and G3 were fed on basal diets, supplemented with EP extract and vitamin C at the doses of 500 mg kg−1 and 400 mg kg−1, respectively. Meanwhile, G4 was fed on a basal diet, supplemented with a mixture of EP extract and vitamin C. After 28 days of feeding, the intestinal tissues were collected for histological observation and immune status, was based on an assay for measuring the phagocytic activity. Furthermore, the expression of the transforming growth factor-beta 1 (TGF-β1), interleukin-1beta (IL-1β), and tumor necrosis factor alpha (TNF-α) genes was evaluated in intestine and head kidney. The results revealed that the G4 successfully surpassed the other groups in terms of the heights of intestinal villi, the number of goblet cells and intraepithelial lymphocytes (IELs), and the phagocytic activity, followed by the G3 and G2. The expression of the IL-1β and TNF-α genes were up regulated only in G4 but in the G3 only the expression of the IL-1β gene was up regulated. Hence, EP extract along with vitamin C could be used as a feed additive in order to improve the structure of the intestinal mucosal epithelium and immune response in tilapia.

Immunostimulants have been found to be attractive and promising agents for disease management in aquaculture. The current study aimed to assess the impacts of feeding with Spirulina platensis (SP) and Salvia officinalis (SO) for 28 days on the immune status of Nile tilapia (Oreochromis niloticus). A total of 180 Nile tilapia (30.6 ± 0.12 g) were divided into 3 groups (triplicates of 20 fish/group). Control group was fed on a basal diet only, while the other two groups were supplemented with SP (10 gm/kg diet) and SO (7.5 gm/kg diet) respectively. Both of SP and SO showed in vitro antimicrobial activity against Pseudomonas aeureginosa. The immune response of Nile tilapia supplemented with SP and SO revealed significant increases in lysozyme, nitric oxide activities and IgM titer with enhancement of IL-1β and TNF-α genes expression before and after infection with P. aeureginosa. Fish challenged with P. aeureginosa showed signs of infection with high mortality rate and low relative percentage survival which elevated to be 83% in SP group and 75% in SO group. It could be concluded that dietary supplementation with SP and SO improved immune response and protected Nile tilapia against infection. Moreover, SP showed better results than SO before and after infection.