Tissues Of Oreochromis Niloticus Research Articles

Level of Heavy Metals in Fish and Associated Human Health Risk From the Omo Delta in Southern Ethiopia: A First-Hand Report.

This study was the first to investigate the levels of heavy metals in commercially important fish species (Lates niloticus and Oreochromis niloticus) and the human health risk in Southern Ethiopia. Sixty fish samples were collected from the Omo delta. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) were used to estimate the human health risks. The mean levels of heavy metals detected in the liver and muscle of Lates niloticus generally occurred in the order of Fe> Zn > Pb > Cu >Mn> Cr > Co > Ni and Fe > Pb > Zn >Mn > Cu > Co > Cr >Ni, respectively. Similarly, the mean levels of iron in the muscle and liver tissues of Oreochromis niloticus were in the order of Fe > Pb > Zn >Mn> Cu > Cr > Co > Ni and Pb > Fe > Zn >Mn> Co > Cu > Ni, respectively. The THQs in the muscle of L. niloticus and O. niloticus decreased in the order Pb > Cr > Cu >Mn> Co > Zn > Fe> Ni and Pb >Mn> Co > Cu > Zn > Ni> Fe respectively. Pb had the highest THQ value in L. niloticus and O. niloticus, which were 0.61 and 0.409, respectively in adult. Similarly, Pb had noted that, L. niloticus and O. niloticus had the highest THQ values, at 0.87 and 0.58, respectively in children. The HI values due to consumption of L. niloticus muscle were 0.668 for adults and 0.942 for children. The mean concentrations of Pb and Cr in the tissues of L. niloticus and O. niloticus were above the FAO/WHO permissible limits. Consequently, investigating heavy metal pollution levels in fish and human health risks from the Omo delta is imperative for addressing environmental and public health concerns.

Toxicological Effects of Lead Nitrate on Biochemical Parameters of Fresh Water Fish Oreochromis niloticus

Freshwater systems are exposed to a variety of pollution sources, such as industrial waste, domestic sewage, agricultural disposal and mining processes. Most of the heavy metals entering into the food chain cause physiological damage for aquatic organisms. The toxicological effects of heavy metals are to non-target organisms like freshwater fishes. Lead is the most important heavy metal that causes bio accumulative toxicity in fish and other aquatic organisms. Lead nitrate is one of the heavy metals, that are found in the environment and causes many adverse effects. Oreochromis niloticus is an important species in commercial fisheries in the world. Human consumption of heavy- metal polluted water can have direct or indirect effects on human health. The present study analyzed the accumulation of heavy metals in water, fish Nile tilapia and also conducted a health risk assessment on humans. In the present study, the 96h LC50 values recorded for lead nitrate was 43ppm.The fish Oreochromis niloticus were treated for the sub lethal concentration of 1/10th,1/20/ and 1/30of lead nitrate (Pb (NO3)2) for the period of 30 days to get biochemical variations of different tissues in the Gill, Liver, Muscle and Kidney. The decreased level of Carbohydrate observed in Lead nitrate exposed fish at all the sub lethal concentrations (1/10, 1/20 and 1/30). The level of total protein and Lipid concentrations were decreased in Gill, Liver, Muscle and Kidney of lead nitrate treated fish Oreochromis niloticus. The depletion of protein, lipid, Carbohydrate content in Gill, Liver, Muscle and Kidney tissues of Oreochromis niloticus was due to the toxicant stress caused by Heavy metal Lead nitrate. A questionnaire-based dietary survey was conducted in 1000 healthy humans from the general population at various fish markets in various places of Krishnagiri district, Tamilnadu. Dietary data were collected in detail through face-to-face interview only on tilapia consumption. Intake (g) was computed. Statistical analyses were conducted using SPSS for Windows and all tests were considered significant at p< 0:05
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Protective Effect of Nitrilotriacetic Acid on Lead Toxicity in Muscle and Liver Tissues of Oreochromis niloticus

Bu çalışmada Kurşun (Pb)’un sublethal derişimlerinin ve Pb + NTA (Nitrilotriasetik asit) karışımının, 7 ve 21 gün süreyle, etkisine bırakılan tatlısu balığı O. niloticus’un kas ve karaciğer dokularındaki bazı enzim aktiviteleri ve oksidatif stres düzeyi incelenmiştir. Parametreler, otoanalizatör cihazlarla ölçülmüştür. Elde edilen veriler neticesinde; karaciğer dokusunda total oksidan (TOS), oksidatif indeksi (OSİ) düzeyleri ile alanin transaminaz (ALT), γ-glutamyl transferase (GGT), alkalin fosfataz (ALP) ve laktat dehidrojenaz (LDH) enzim aktivitelerinde artış, total antioksidan (TAS) düzeyinde azalış gözlenmiştir. Kas dokusunda ise TOS, OSİ düzeyleri ile ALT enzim aktivitesinde artış gözlenirken TAS düzeyi ile GGT ve ALP enzim aktivitelerinin kontrol seviyesinde olduğu saptanmıştır. NTA’nın varlığında bazı parametreler görülen azalma veya artmaların daha hafif olduğu gözlenmiştir. Sonuç olarak Pb’nin balığın fizyolojisinde değişikliklere neden olduğu, NTA’nın bu değişiklikleri kısmen de olsa azalttığı söylenebilir.

Health Risk Assessment and Levels of Heavy Metals in Farmed Nile Tilapia (Oreochromis niloticus) from the Volta Basin of Ghana

Heavy metals (Pb, Cd, As, Mn, Fe, Zn, Cu, Ni, and Cr) are some of the most toxic elements that can bioaccumulate from sources linked to human activities, such as industry and agriculture. This study quantifies the concentrations of several heavy metals in caged tilapia found in Ghana’s Volta Basin and assesses the associated health risks. The levels of heavy metals in the tissues of Oreochromis niloticus from three cage farms (N = 52) were determined using Atomic Absorption Spectrometry (AAS). The implication for human health was assessed using several risk assessment techniques. Fe (50.11 ± 10.22 mg/kg) and Cr (0.31 ± 0.07 mg/kg) had the highest and lowest accumulated metal concentrations, respectively. Heavy metal concentrations in tilapia tissue from fish farms were ordered as follows: Fe > Mn > Zn > Ni > Cr (farm A), Fe > Zn > Ni > Mn (farm B), and Fe > Mn > Zn > Ni > Cr (farm C). All metals had an estimated daily intake (EDI) below the threshold, and mean differences between sample farms were not statistically significant. Similarly, the values of target hazard quotients (HQs) and hazard indices (HIs) were less than one. According to the risk assessment results, eating tilapia from farms posed no risk to human health. The presence of Mn, Fe, and Ni concentrations above the maximum level in the fish, on the other hand, suggests that they may affect fish health.

Bioaccumulation test of cadmium and magnesium in the liver of Oreochromis niloticus via Scanning electron microscope

In this present study, the bioaccumulation of heavy metal, cadmium (Cd) and major element magnesium (Mg), in the liver tissues of Oreochromis niloticus, was investigated after exposing the fish over 96 h period to Cd LC50 (0.8 mg/l) and Mg LC50 (3.03 mg/l). These tissues were investigated by light and scanning electron microscopy. Scanning electron microscopic X-ray microanalysis of fish liver exposed to Cd or Mg confirmed that these metals were accumulated in liver tissues.

Environmentally relevant pesticides induce biochemical changes in Nile tilapia (Oreochromis niloticus).

The high demand for food consequently increases the entry of agricultural residues into water resources, and this phenomenon can affect non-target organisms in different ways. Environmentally relevant pesticide effects (per se or in combinations) are scarce in the scientific literature. Therefore, the aim of this study was to investigate: (1) the presence of pesticide residues in an important Brazilian source of water supply and power generation (Jacuí river), during 1 year of monitoring. (2) in a laboratory study verify the effects of the most frequently, herbicide, fungicide, and insecticide found in Jacuí river (individualized or in a mixture) on biochemical parameters in different tissues of Oreochromis niloticus. Twenty pesticide residues were detected in superficial water samples, and two of them are banned in Brazilian territory. Atrazine (0.56 µg L-1), azoxystrobin (0.024 µg L-1), and imidacloprid (0.11 µg L-1) were the most frequently herbicide, fungicide, and insecticide, respectively, found in the river and were used in the laboratory assay. O. niloticus exposed to the pesticide mixture exhibited more biochemical effects than individualized exposure groups. This response can be a result of the combined pesticide effects, culminating in an additive or synergistic effect, depending on the biomarker. In individual exposure groups, atrazine presented the most pronounced alterations, followed by azoxystrobin and imidacloprid. Overall, pesticide exposure increased levels of oxidative stress parameters, reduced antioxidant enzyme activities, and induced acetylcholinesterase activity. These findings highlight the threat to aquatic organisms which may be exposed to a miscellaneous of toxic compounds in the environment.

Effect of Cadmium on SOD Activity in different Tissues of Oreochromis niloticus

Bu çalışmada kadmiyum’un Oreochromis niloticus’da superoksit dismutaz (SOD) aktivitesi üzerine etkileri araştırılmıştır. Balıklar 0.2, 1.0 ve 2.0 mg/L Cd derişimlerinin etkisine 15 ve 30 günlük sürelerle bırakılarak karaciğer, solungaç, böbrek ve kas dokularında superoksit dismutaz (SOD) aktiviteleri belirlenmiştir. Kadmiyumun farklı derişimlerinin etkisine bırakılan O. niloticus'un karaciğer, böbrek, solungaç ve kas dokularında süperoksit dismutaz (SOD) enzim aktivitesi kontrol değerleriyle ile karşılaştırıldığında önemli değişiklikler belirlenmiştir. Kadmiyumun denenen yüksek derişimleri karaciğer dokusunda süperoksit dismutaz (SOD) aktivitesinin azalmasına, böbrek dokusunda ise bir artışa neden olmuştur.

Moringa Oleifera Leaf Extract Repairs the Oxidative Misbalance following Sub-Chronic Exposure to Sodium Fluoride in Nile Tilapia Oreochromis niloticus.

Simple SummaryThe present study investigated the antioxidant effect of ethanolic extract of Moringa Oleifera (MO) leaves against sodium fluoride-induced toxicity in Nile tilapia. It is concluded that MO leaves are a promising antioxidant plant via downregulation of lipid peroxidation, and upregulation of antioxidant enzyme activity including SOD, CAT, GPx, GSH, and TAC in liver, kidney, gills, and muscle tissue in a time-dependent manner, in addition to downregulation of mRNA expression of antioxidant-related genes.The potential antioxidant property of Moringa oleifera (MO) has been the recent focus of an increased number of studies. However few studies investigated its antioxidative ability against sodium fluoride-induced redox balance breakdown in Oreochromis niloticus. Thus, this study evaluates the effects of MO against the oxidative stress induced by sub-chronic exposure to sodium fluoride (NaF). A total of 264 fish (40 ± 3 g BW) were used to calculate the 96 hr-LC50 of NaF and perform the sub-chronic exposure study. 96 hr-LC50 of NaF was calculated as (61 mg/L). The 1/10 dose of the calculated 96 hr-LC50 (6.1 mg/L) was used to complete the sub chronic exposure for eight weeks. Fish were divided into four groups (n = 51; three replicates each); control, non-treated group; NaF group (exposed to NaF 6.1 mg/L); MO group (treated with 1% MO of diet); and NaF+MO (exposed to NaF 6.1 mg/L and treated with 1% MO of diet). The results revealed that the sub-chronic exposure to NaF (6.1 mg/L) was substantially increased malondialdehyde (MDA) and decrease the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reduced (GSH), glutathione peroxidase (GPx), and total antioxidant capacity (TAC) in the gills, liver, kidney, and muscle tissue in a time-dependent manner. In addition, a significant reduction in mRNA expression of GST in the liver was reported following NaF exposure. On the contrary, dietary supplementation of MO to NaF-exposed fish resulted in a significant reduction in MDA levels, and a significant elevation of SOD, CAT, GSH, GPx, and TAC activities in a time-dependent manner, in addition to significant elevation of GST mRNA expression in liver tissue. It could be concluded that a 1% MO (w/w) ration is a promising antioxidant plant that may successfully use to interfere with the oxidation processes induced by NaF in various tissues of Oreochromis niloticus.

Cıva toksisitesi üzerine selenyumun koruyucu rolünün Oreochromis niloticus (Linnaeus, 1758)’ta katalaz, süperoksit dismutaz ve malondialdehit parametreleri ile değerlendirilmesi

In this research, to determine toxicity of mercury (Hg) and whether selenium (Se) has any role in protection of this toxicity, it was investigated the alterations in oxidative stress parameters in tissues of Oreochromis niloticus. For this purpose, fish were exposed to 0.01 and 0.05 ppm Hg and 0.01 ppm Hg+0.01 ppm Se and 0.05 ppm Hg+0.05 ppm Se for 4 and 21 days and activities of superoxide dismutase (SOD) and catalase (CAT) and levels of malondialdehyde (MDA) in gill and liver were determined. It was observed significant changes in all analyzed parameters due to tissue, medium concentration and exposure period in the exposure of mercury alone and Hg+Se mixtures. In Hg alone, and in combination with Se especially in their higher medium concentrations, activities of SOD and CAT in the gill and liver significantly increased at 4 days (P˂0.05), while they significantly decreased at 21 days (P˂0.05). In the exposure of Hg and Hg+Se and in the both tissues, it not determined significant alteration in the MDA levels at 4 days (P˃0.05), while they elevated in their higher concentrations at 21 days (P˂0.05). In conclusion, it was determined the increases or decreases in activities of SOD and CAT and levels of MDA in O. niloticus were higher in the Hg alone than Hg+Se mixtures and selenium has a protective effect on oxidative toxicity of mercury.

Determination of Toxic Effects of Biopesticide Emamectin Benzoate in the Tissues of Oreochromis niloticus by Acetylcholinesterase Enzyme Activity

Bu çalışmada emamectin benzoate’ın Oreochromis niloticus’da AChE aktivitesi üzerine etkileri araştırılmıştır. Balıklar 110 ve 220 µg/L emamectin benzoate etkisine 96 saat ve 14 günlük sürelerle bırakılarak beyin, karaciğer ve böbrek dokularında asetilkoinesteraz (AChE) aktiviteleri belirlenmiştir. Emamectin benzoate maruz bırakılan O. niloticus'un beyin, karaciğer ve böbrek dokularında asetilkoinesteraz (AChE) enzim aktivitesi kontrol değerleriyle ile karşılaştırıldığında önemli değişiklikler belirlenmiştir Emamectin benzoate’a maruz bırakılan O. niloticus'un beyin, karaciğer ve böbrek dokularında AChE aktivitesi kontrol değerleriyle ile karşılaştırıldığında tüm sürelerde azaldığı belirlenmiştir.

Copper Accumulation in Tissues of Oreochromis niloticus Exposed to Copper Oxide Nanoparticles and Copper Sulphate with Their Effect on Antioxidant Enzyme Activities in Liver

Copper accumulation in the gill, liver, kidney, spleen, and muscle tissues of Oreochromis niloticus was determined after exposing the fish to 10, 50, and 100 μg Cu/L applied as copper sulphate (CuSO4) and copper oxide nanoparticles (CuO NPs) after 1, 7, and 15 days. Changes in the liver SOD, CAT, and GPx activities influenced by this accumulation were also studied. No mortality was observed during the experiments. Copper levels increased in the gill, liver, kidney, and spleen tissues of O. niloticus compared to control when exposed to both CuSO4 and CuO NPs, whereas no accumulation was detected in muscle tissue at the end of the exposure period. Highest accumulation of copper was observed in the order of the liver, kidney, spleen, and gill tissues, respectively. SOD, CAT, and GPx activities increased in the liver tissue at the end of the exposure period. Overall, CuO NPs are more effective than CuSO4 in terms of tissue accumulation and liver enzyme activities.

Effects of Clinoptilolite on Copper Accumulation of Oreochromis niloticus

The copper accumulation in liver and gill tissues of Oreochromis niloticus, exposed to 2 ppm Cu
 and 1g/L clinoptilolite singly and to the same concentrations of their mixture over 24, 48, 72 and
 96 hours was studied. ICP-AES spectrophotometer techniques were applied in determining tissue
 copper levels. Statistical evaluation of the experimental data was carried out by Student Newman
 Keul’s procedure. No mortality was observed during the experiments. Copper accumulation was
 lower in metal-clinoptilolite mixture group than metal singly group in gill tissue while no
 accumulation in both experimental groups in liver tissue (P<0.05). In addition, the copper level in
 the liver was lower in all experimental groups than in the control (P<0.05). Low Cu accumulation
 in gill tissue exposed in mixture groups can be explained by copper adsorption with chelating
 agent. The decrease of Cu reserves in the liver can be expressed by increase of copper-containing
 enzyme and protein synthesis.

Metal accumulation in two contiguous eutrophic peri-urban lakes, Chivero and Manyame, Zimbabwe

Concentrations of aluminium, cadmium, chromium, cobalt, copper, iron, lead, nickel and zinc were determined in surface water, benthic sediments, and the gills, liver and stomach muscle tissues of Oreochromis niloticus and Clarias gariepinus in peri-urban lakes Chivero and Manyame, Zimbabwe. Five sites were sampled in each lake once per month in November 2015, February, May, August and November 2016. Pollution load index detected no metal contamination, whereas the geo-accumulation index reflected heavy to extreme sediment pollution, with Fe, Cd, Zn, Cr, Ni and Cu present in both lakes. Significant spatial temporal variations were detected for Al, Cr, Cu and Pb across sites within and between the two lakes. High Fe, Al and Cr concentrations in water and sediments in lakes Chivero and Manyame derive from geogenic background sources in addition to anthropogenic loads and intensity. Elevated concentrations of Al, Pb, Cu, Cd, Fe and Zn detected in gills, liver and stomach tissue of catfish corroborate concentrations in water and sediments, and pose the highest ecological and health risk for hydrobionts in lakes Chivero and Manyame. Contiguity of peri-urban lakes exposes them to similar threats, necessitating creative water management strategies, which ensure ecological continuity.

Oxidative Stress Parameters, Induction of Lipid Peroxidation, and ATPase Activity in the Liver and Kidney of Oreochromis niloticus Exposed to Lead and Mixtures of Lead and Zinc.

The purpose of this investigation was to evaluate the effects of lead (Pb) and lead + zinc (Zn) combination on the oxidative stress, total ATPase and Pb accumulation in the tissues of Oreochromis niloticus (Linnaeus, 1758). The fish were exposed to 0.1mg/L Pb (T1), 1.0mg/L Pb (T2) and mixtures of 0.1mg/L Pb and 0.5mg/L Zn (M1); 1.0mg/L Pb and 5.0mg/L Zn (M2) for 7 and 21days. Pb accumulation, total ATPase activity, several antioxidant enzyme activities such as catalase, glutathione peroxidase (GPX), glutathione S-transferase, glutathione reductase, and thiobarbituric acid reactive substances concentrations were measured in the liver and kidney tissues. Metal accumulation in the tissues was higher in Pb exposure compare with mixtures of Pb and Zn exposures. Beside the inhibition of liver GPX activity, general increases of antioxidant enzyme activities in the tissues were recorded after metal exposures. This investigation emphasizes the oxidative stress in O. niloticus caused by Pb, and adaptation of the organisms to the changes in enzyme activities.

Waterborne and Dietary Copper Accumulation in Various Tissues of Oreochromis niloticus

Waterborne and Dietary Copper Accumulation in Various Tissues of Oreochromis niloticus

Effects of Copper Oxide Nanoparticles on Antioxidant Enzyme Activities and on Tissue Accumulation of Oreochromis niloticus.

Accumulation of copper oxide nanoparticles (CuO NPs) in gill, liver and muscle tissues of Oreochromis niloticus and its effects on superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities in gill and liver tissues were studied after exposing the fish to 20µg/L Cu over 15days. Copper levels and enzyme activities in tissues were determined using spectrophotometric (ICP-AES and UV) techniques respectively. No mortality was observed during the experiments. Copper levels increased in gill and liver tissues of O. niloticus compared to control when exposed to CuO NPs whereas exposure to metal had no effect on muscle level at the end of the exposure period. Highest accumulation of copper was observed in liver while no accumulation was detected in muscle tissue. SOD, CAT activities decreased and GPx activity increased in gill and liver tissues when exposed to CuO NPs.

Effects of Lead and Selenium Interaction on Acetylcholinesterase Activity in Brain and Accumulation of Metal in Tissues of Oreochromis niloticus (L., 1758)

The potential accumulation of lead in different tissues of Oreochromis niloticus and the effects of selenium in AChE inhibition caused by lead in brain were investigated. Juvenile O. niloticus samples were exposed to combination of 1 mg L-1 and 2 mg L-1 lead and 1mg L-1 lead+2mg L-1 selenium and 2mg L-1 lead+4mg L-1 selenium for 1, 7 and 15 days respectively. The accumulation of lead in gill, brain, liver and muscle tissues was analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) as well as brain acetylcholinesterase (AChE, E.C.3.1.1.7) enzyme activity was also analyzed by spectrophotometric method. No mortality was observed during lead exposure in relation to time period and exposed concentrations. Lead accumulation was occurred in all tissues in relation to time. Maximum lead accumulation occurred in brain tissue, followed by the liver, gills and muscle tissues in relation to time period. Selenium caused a decrease on accumulation of lead in tissues (all selenium mixtures in muscle tissue on the first day, 1mg L-1 Pb+2mg L-1 selenium in gill tissue on the seventh day, in liver tissue on the seventh day except 2mg L-1 Pb+4mg L-1 selenium mixtures) at the end of each of all three test periods. Inhibition of AChE activity was caused by the highest concentration and by the short-term effect of lead. Such effect of lead was eliminated by selenium mixture. Lead and selenium mixture were resulted an increase in activity on 15th day at the highest concentration. Selenium led to decrease in the accumulation of lead in the tissues and caused to improvement in the loss of AChE activity.

Effects of copper oxide nanoparticles on antioxidant enzyme activities in gill and liver tissues of Oreochromis niloticus

Effects of copper oxide nanoparticles on antioxidant enzyme activities in gill and liver tissues of Oreochromis niloticus

Biomonitoring Of Some Heavy Metals In Water Of El Salam Canal using Oreochromis niloticus As Bioindicator

This study was initiated to assess the levels of (Fe, Cu, Cd, Pb, Zn, Co, Mn and Ni) in water samples and Oreochromis niloticus tissues (muscles, gills and liver) collected from Fum El-Salam canal, Hadous drain and mixing point of El-Salam canal with Hadous drain throughout Summer 2014. Levels of physicochemical parameters of water samples (TDS, EC and ammonia) were significantly high (P<0.05) in Hadous drain and mixing point of El-Salam canal with Hadous than the permissible levels of the law 48/1982. The results showed that Zn, Fe, Mn and Cu recorded 1.612±0.6-<0.001-0.011±0.001,0.56±0.29- 0.479 ± 0.03- 0.075±0.01, 0.25±0.028 - 0.179±0.01 - 0.046±0.003, 0.045± 0.01 - 0.019±0.01 - 0.009±0.007 mg/l in Hadous drain, Mixing point and Fum El-Salam canal respectively, while the increase in Zn and Mn for Hadous drainage exceeded the permissible values sets by USEPA (1996). The discharging of Bahr Hadous drainage water to El-Salam canal leads to alteration in water quality of El-Salam canal as it increases heavy metals loads which implicate pollution, such deterioration showed in the studied tissues of Oreochromis niloticus. It is recommended to treat the different wastes before discharging to El-Salam canal.

Heavy Metals (Pb, Fe and Zn) in Fish Due to Water Toxicity

Water Toxicity is a worldwide problem, heavy metals belonging to the most important pollutants. The progress of industries has led to increased emission of pollutants into ecosystems. The fish were divided into four groups, control group and three groups exposed to 5, 10 and 15 mg/l of lead acetate, 10, 20 and 30 mg L-1 of ferric chloride and 10, 20 and 300 mg L-1 of zinc sulfate respectively, the experimental fish were exposed to treatment for periods of 15 days, 30 days and 45 days. The Nile tilapia was exposed to water pollution with lead, iron and zinc. The Nile tilapia 80 - 100 gm body weight was obtained from Abbassa farm. The fish were reared in large tanks contained water from their farm. The fish were acclimatized and fed on 30 % protein diet. Result of the present study revealed that lead concentrations in the tissues of the fish were elevated and highest contamination were increased in the gill and liver than that in the muscles. Also, there was vary significant increase in the concentrations of lead in the gill, liver and muscles tissues of Oreochromis niloticus exposed to different concentrations of lead acetate than that control fish tissues. Iron concentrations in the tissues of the fish were elevated in the gill and liver than that in the muscles. Also, there was vary significant increase in the concentrations of iron in the gill, liver and muscle tissues of O. niloticus exposed to different concentrations of ferric chloride at different period than that control fish tissues. Zinc concentrations in the gill and liver were higher than that in the muscles. Also, there was significant increase in the concentrations of zinc in the gill, liver and muscle tissues of O. niloticus exposed to different concentrations of zinc sulfate at different period than that control fish tissues. Results generally showed that metal concentrations were always lowest in the muscles and highest in the gill and liver.