Pollution of water bodies in most developing countries is of grave concern since toxic pollutants interact with the genetic blueprints of aquatic organisms leading to a variety of illnesses. In this study, histological changes in the gills, liver and kidney as well as the genotoxic effect of water sample from Apodu reservoir, were investigated in the peripheral erythrocytes of cultured catfish (Clarias gariepinus) using micronucleus assay. They were exposed to the water sample for a period of 3, 7 and 14 days. The physico-chemical (pH, temperature, transparency) and heavy metals analysed (Ca>Mg>Fe>Zn>Mn>Cu>Ni=Pb=Cd=Cr) were all within the acceptable limit permissible. However, the micronucleus test shows statistically significant (p<0.05) induction of micronuclei and nuclear abnormalities as compared to the control (borehole water). The histopathological analysis shows some mild alterations in the organs such as distortion and infiltration of lymphocytic cells of the gills. We also reported mild distortion of hepatic tissue of the liver as well as abnormal nephron and glomeruli with congestion and vascular dilation of the kidney. These alterations might be due to anthropogenic activities that pollute the water body. Therefore, the influx of agricultural and domestic waste into the Apodu reservoir should be discouraged as part of remediating efforts.

Background Pollution arising from the noxiousness of palm oil mill effluent (POME) has become a serious threat to aquatic biotas. However, a paucity of information exists on fish response to POME-mediated oxidative stress, lipid peroxidation, haemato-biochemical, enzymatic and ionic changes. This study, therefore, evaluates the effects of 28-day exposure of Heteroclarias, a hybrid catfish, to POME. Juvenile Heteroclarias (n = 350, average weight: 11.90 ± 0.70 g and average length: 9.04 ± 0.71 cm) were exposed to sublethal concentrations (0-control, 4.00, 8.00 and 12.00 mg/l) of POME to determine its effects on red blood cells (RBC), haemoglobin (HB), packed cell volume (PCV), white blood cells (WBC), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and mean cell volume (MCV). The activities of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST), lactate dehydrogenase (LDH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and the levels of malondialdehyde (MDA), calcium (Ca+), potassium (K+), magnesium (Mg2+) and sodium (Na+) ions were also assayed in the gill and liver. Results Exposure to POME caused significant (p < 0.05) concentration-dependent decrease in RBC, HB, PCV, MCV, MCH and MCHC values, whereas a significant (p < 0.05) concentration-dependent increase in WBC was observed in POME-exposed fish compared to the control. ALT, AST, LDH, GPx, SOD and CAT activities in the gill and liver significantly (p < 0.05) increased in a concentration-dependent manner. MDA level significantly (p < 0.05) increased in the gill relative to control, while in the liver it was insignificantly different. Both tissues exhibited an increase in Ca+, K+, Mg2+ and Na+ levels at the highest toxicant concentration with a rise of 77.93, 38.46, 109.54 and 41.99% recorded for the electrolytes in the gill and 79.17, 26.92, 55.48 and 38.78% in the liver above the control value, respectively. The levels of all the electrolytes except K+ were higher in the gill than the liver and were in the order: Na+ > K+ > Mg+ > Ca2+ in both tissues. Conclusions These results may be used as a suitable tool for pollution assessment and policy formulation to mitigate the discharge of untreated POME into aquatic ecosystems and their impacts on resident organisms.

Background Atrazine has impacted negatively on fish by inducing significant alterations in their haematological, biochemical and histological parameters. Mitigating such alterations to enhance fish survival becomes pertinent. Unfortunately, readily available and eco-friendly remedies are scarce. The study, therefore, investigated the potential ameliorative effects of dietary supplementation of aqueous Carica papaya and Mangifera indica leaf extracts on atrazine-induced toxicity and oxidative damage in the tissues of Clarias gariepinus. Fish (average weight: 10.57 ± 1.69 g, and average length: 10. 36 ± 1.26 cm) were randomly divided into six groups of ten samples each. Group I served as control and administered borehole water only, group II was exposed to 8.50 µg/l atrazine corresponding to ¼ of 96 h LC50, group III was treated with low (0.25 mg/g) concentration of each extract alone, group IV was exposed to 8.50 µg/l atrazine and treated with the low concentration of each extract, group V was administered with high (0.75 mg/g) concentration of each extract alone, and group VI was exposed to 8.50 µg/l atrazine and treated with the high concentration of each extract. The experiment spanned 28 days after which the haematological, biochemical and histopathological alterations were assayed. Results Atrazine intoxication significantly induced oxidative damage in the gill and liver, culminating into different histopathological disorders, decreased haematological parameters, increased serum, gill and liver levels of malondialdehyde and enzyme biomarkers (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and acetylcholinesterase). On the other hand, atrazine exposure caused decreased levels of glucose, protein and superoxide dismutase in the tissues. Treatment with diets fortified with both extracts significantly increased all the decreased haematological parameters, reduced the serum levels of the elevated malondialdehyde and tissues enzyme biomarkers in a concentration-dependent manner. Biochemical parameters in the tissues were also improved with dietary supplementation of the extracts. Histopathological examination of both tissues showed ameliorating effects of both extracts in restoring the structural and functional integrity of each tissue. Conclusions These results suggest that the extracts have ameliorative potentials against atrazine-induced peroxidative injury in C. gariepinus. The utilisation of these extracts could enhance better health management practices, particularly in a rice-cum fish culture, where atrazine application is common.

Indiscriminate discharge of home, agricultural, and industrial wastes into water bodies, most rivers and reservoirs around the world are becoming polluted. The ecotoxicological potential of this in fish species gathered from important reservoirs and rivers in Ilorin, Nigeria, was explored in this study. Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) water samples were collected and physicochemical characteristics were investigated at five distinct sites: Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) (Harmony). In Tilapia zillii and Clarias gariepinus, we measured serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gills, lungs), and serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) as a biomarker for oxidative stress, while micronucleus and comet assays were used to detect DNA damage. Except for DO, which was very low in the two rivers, the physicochemical parameters and heavy metals evaluated in the five separate water bodies were within the allowed levels of the NSDWQ and WHO standard for drinking water. In comparison to the Unilorin, Apodu, and Asa reservoirs, a slight increase in Pb was observed across the five sampling sites, which could contribute to increased biochemical and haematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA, and DNA single strand break in T. zillii and C. gariepinus collected from Asa rivers. This could be due to the indiscriminate dumping of effluents from adjacent industries, agricultural wastes, and household wastes into rivers.

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Heterobranchus longifilis juveniles (n = 450, Mean length ± SD = 10.28 ± 1.34 cm) were exposed to varying concentrations (0 = control, 6.00, 8.00, 10.00, 12.00 mg/l) of zinc oxide nanoparticles (ZnO-NPs) for 60 days to determine its effects on the histopathology of the gill and liver. To evaluate recovery from ZnO-NPs exposure, fish were subjected to a 30-day depuration. Ascorbic acid (AA) ameliorative potential against ZnO-NPs toxicity was assessed by augmenting fish basal diet with different AA (50.00, 250.00, 500.00, 1000.00 mg.kg -1) levels. After each experiment, fish gills and liver were removed for histopathological analysis. Gills of exposed fish revealed different alterations like epithelial hyperplasia, epithelial lifting, lamellar fusion, oedema, aneurysms, and necrosis; while alterations such as nuclear vacuolation, fatty degeneration, cytoplasmic degeneration, focal fibrosis and necrosis were recorded in the liver. The mean degree tissue change (DTC) in both organs of ZnO-NPs-exposed fish gradually increased with increase in ZnO-NPs concentration and exposure period. After 30-day depuration, some of the lesions in both organs attained recovery, while others did not. AA administration to ZnO-exposed fish at 500 mg.kg -1 completely reversed the lesions in both organs compared to the normal tissue architecture in the control. The results suggest that ZnO-NPs could trigger structural alterations in both the branchial and hepatic tissues of H. longifilis, and full recovery under depuration was slow. However, 500 mg.kg -1 AA dietary supplementation have the propensity to ameliorate the ZnO-NPs-induced pathological lesions in H. longifilis.Concentration (mg/l) 0.00 (Control)

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Hydrocarbons and heavy metals (HM) present in automobile wastes get into water bodies close to automobile mechanic villages. They deteriorate the physico-chemical qualities of such water bodies and exert toxic effects on fish and other aquatic fauna. They also pose risks to humans that consume fish from streams near such automechanic villages. There is paucity of information on the HM contents of Agba stream, Ilorin and no information on the bioaccumulation of HM in the tissues of Pellonula afzeliusi is currently available. The purpose of this study was to assess the physico-chemical qualities of water and bioaccumulation of HM in the tissues of Pellonula afzeliusi fish collected from Agba stream, Ilorin, Kwara State, Nigeria. Water and samples of Pellonula afzeliusi were collected from the upstream (station A), midstream (station B) of Agba stream located close to an auto-mechanic village and Oyun dam (control site, station C) located within the University of Ilorin. Standard methods were used to analyse oil and grease (OG), total petroleum hydrocarbon (TPH) and HM in water samples. The concentrations of TPH and HM were analysed in the skin, bone, muscle, gills, gastrointestinal tract, liver and kidney of the fish. The order of water HM concentrations indicated Zn > Cd > Ba> Fe > Pb at station A; Cd > Zn > Fe > Ba > Pb at station B, and Zn > Ba > Pb > Fe >Cd at station C. TPH and HM bioaccumulated in the tissues of fish while lead was not detected in all tissues from station C. Bioaccumulation factor varied with the highest values  t station C. The result of this study indicated heavy pollution burden in station B with lower pollution burden in station C (the control site). These call for attention of government in ensuring ecological restoration and prevention of further discharge of automobile wastes into the stream. Keywords: Automobile wastes, Heavy metals, Hydrocarbons, Bioaccumulation, Pellonula afzeliusi