The assessment of heavy metals concentration in Tiga dam, Nigeria vis-à-vis their bioaccumulation and histopathological alterations in Auchenoglanis occidentalis from it were carried out. The water of the dam and the liver of the fish were analyzed for zinc (Zn), cadmium (Cd), lead (Pb) and iron (Fe) concentrations and their bioaccumulation factors. At the same time, the gills, liver and kidney of the exposed fish were also examined for histopathological alterations. The results revealed that concentrations of the metals differs significantly (p < 0.05) between the dam’s water and the liver of the sampled fish. Liver bioaccumulations of the metals were in the order of Zn > Fe > Cd > Pb. However, the degree of tissue alterations in the gills showed their normal functioning despite the observed alterations while liver and kidney were mildly and moderately damaged, respectively. This indicated that Zn, Cd, Pb and Fe polluted the dam.

Department of Veterinary Public Health and Preventive Medicine, University of Abuja, Abuja, Nigeria*Correspondence: Tel.: +2348187384271; E-mail: seabalaka@yahoo.co.uk Abstract Escherichia coli infection was diagnosed in 5-week old broiler chickens raised intensively on a medium-sized commercial farm in Gaube-Kuje, Abuja, Nigeria. Signs of weakness, depression and inappetance with ruffled feathers and pasted vents were reportedly observed in affected birds within the flock. Detailed post mortem examinations revealed diffuse splenomegaly and hepatomegaly with multifocal greyish areas on their surfaces while the diffusely enlarged kidneys were congested with mottled pale appearance. Histopathologically, the liver of affected broilers showed diffuse congestion, multifocal coagulative necrosis and cellular infiltration. Generalized perivascular and inter-septal oedema and haemorrhage were observed in the lungs of affected broilers with generalized lymphocytic depletion within the spleen as well as locally extensive congestion and haemorrhage within the kidney, and cellular infiltration and necrosis within heart musculatures. Microbiological evaluation of liver samples yielded pure E. coli growth only. A diagnosis of colibacillosis, especially colisepticaemia, was made with appropriate treatment based on culture and sensitivity test result involving Levofloxacin (R) . The client was consequently advised to guard against possible predisposing factors as control and preventive measures for the disease outbreak on the farm.

Background and aim: Fish live in direct contact with their immediate external environment and, therefore, are highly vulnerable to aquatic pollutants. We aimed to investigate histopathologic changes in the gills and skin of fish exposed to plant extracts. Methods: Clarias gariepinus adults were exposed to 0 mg/L, 85 mg/L, 100 mg/L, 115 mg/L, 130 mg/L and 145 mg/L concentrations of ethanolic extracts of Parkia biglobosa pods over a 96‐h period. Results: Gills from exposed fish showed hyperemia and severe edema with fusion of secondary lamellae. The skin from exposed fish showed hyperplasia of mucus producing cells, epidermal and dermal polymorphonuclear leukocytic infiltrations with areas of dermal necrosis and aggregation of melanin pigments. Fish from the control group showed no histopathologic changes. Conclusions: Ethanolic extract of P. biglobosa pods is toxic to adult C. gariepinus. Therefore, extensive use of this tree to harvest fish for human consumption should be discouraged pending further investigations to determine the safety of such practices to human health.

Background. Aquatic pollution by heavy metals has become a global problem and is of great concern due to the detrimental effects on aquatic ecosystems and possible human uptake. Objectives. The present study aimed to evaluate tissue bioaccumulations of heavy metals and possible human health risks in addition to associated cellular damages in fish for sale in a fish market in Abuja, Nigeria. Methods. Clarias gariepinus sold at the Kado Fish Market in Abuja, Nigeria, in March–April 2017 and March–April 2018 were randomly purchased and sampled. The heavy metal contents of the sampled fish were assayed and used to assess the extent of potential health risks to human consumers. The extent of histopathological changes associated with the bioaccumulations in the sampled fish were also evaluated according to standard procedures. Results. Levels of most heavy metals were above permissible limits, except for lower levels of zinc (Zn) in liver and muscle and higher levels of lead (Pb) in muscle in the sampled fish. Similarly, significant (p<0.05) liver bioaccumulation occurred for Zinc (Zn), chromium (Cr), iron (Fe), and copper (Cu) compared to their levels in muscle. The total hazard index (non-cancer risk across all metals) was 0.0415, which is very low and acceptable. The cancer risks ranged between the acceptable values of 1.98 × 10−5 – 3.71 × 10−6. Associated histopathological changes, which occurred in the sampled fish, differed between the various assayed tissues. Conclusions. Most of the heavy metals were significantly bioaccumulated (p<0.05) and were above the permissible levels, particularly in liver samples. The levels of muscle heavy metal bioaccumulation in the sampled fish posed no apparent cancer or non-cancer health risks to human consumers. However, further efforts are needed to minimize heavy metal aquatic environmental pollution to safeguard the health of aquatic flora and fauna and human consumers because of the tendency of these pollutants to persist and bioaccumulate to toxic levels over time. Competing Interests. The authors declare no competing financial interests.

This study aimed to evaluate the haematological and biochemical changes in