Heavy metals contamination of Chrysichthys nigrodigitatus and Lates niloticus in Ikere Gorge, Oyo state, Nigeria

This study investigates the presence of heavy metal contamination of Chrysichthys nigrodigitatus and Lates niloticus. Adult C. nigrodigitatus and L. niloticus were obtained from fishermen in Ikere Gorge, Oyo state, Nigeria. Water samples were also collected during the wet and dry seasons of the year in the same locality. The presence of five metals were analyzed in both fish and water. Iron, copper, zinc, lead and manganese were investigated by atomic absorption spectrosocopy (AAS) in two separate experiments. In each case, four tissues; gills, bone, intestine and muscle were compared with the level of metals in the water. Lower concentrations of metals were recorded in water than in fish. Lower concentration of the metals found in fish and water was less than that recommended by the World Health Organisation (WHO) guideline for maximum concentration recorded in the tissue of the two samples. Iron was found to be dominant in the intestine of C. nigrodigitatus, while manganese was found to be highest in the bone of L. niloticus, copper recorded the least of all the metals. There is significant difference (P < 0.05) in heavy metals concentration in the gill of C. niloticus and water, as well as the concentration in the intestine of L. niloticus and water. It was concluded that though the heavy metals of interest were present in measurable quantities, they were still within safe limits for consumption.Key words: Heavy metals, fish, gorge, contamination

The Fin Fish Assemblage of Lower Ogun river, Akomoje Ogun state Nigeria

The fin fish assemblage of lower Ogun river was investigated, which comprised a total of 34 species belonging to 13 families. Chrysicthys nigrodigitatus was most abundant and highest in biomass (55,491.21kg) accounting for 27.58% of the catch. Gnatonemus senegalenses, Gnatonemus cyprinoides, Synodontis nigrita, Marcusenius psittacus and Malapterurus electricus were the least in number, while Phago loricatus was least in biomass (32.03kg) accounting for 0.02%. The major aim was to assess the fish resources of the lower Ogun River and evaluate the water parameters as related to fish production. Data on fish species were collected, using multi-fleet gillnet sampling techniques between May and October 2012. Three sampling stations were randomly selected for the investigation of the fin fish assemblage and abundance. No significant difference was observed in dissolved oxygen, nitrogen, phosphate, water temperature, conductivity, alkalinity, total dissolved solid and pH range values in the river. The water quality parameters were favourable for fish production. Water level and temperature were observed to guarantee high yield in Ogun River.Keywords: Fin Fish, Check list, Ogun River

The effects of heavy metals concentration on some commercial fish in Ogun River, Opeji, Ogun State, Nigeria

A study was conducted on commercially important fish species of heavy metals in water bodies. The primary objectives were to find out the amount of heavy metals concentration in the fish species, sediments and water samples at the deep and shallow part of the river, to determine the toxicity and relationship between the collected samples and the rate at which it pollutes the water. Atomic absorption spectrophotometer (AAS) evaluates their wholesomeness for human consumption. Four heavy metals (lead, cadmium, copper and zinc) were analyzed and only copper and zinc were found to be present in the digested samples. The concentration of copper in the fish (flesh) was 0.09 mg/l and that of zinc was 0.25 mg/l. In the bone samples, copper was found to have 0.17 mg/l and zinc 0.22 mg/l. In the water samples analyzed, the concentration of copper is 0.035 mg/l while that of zinc is 0.047 mg/l. In the sediment sample, the amount of copper is 310.0 mg/kg while that of zinc is 2050.0 mg/kg. This however signifies that the fish species in the Ogun River as well as the water is suitable for consumption which was found to be less than the World Health Organization (WHO) maximum recommended acceptable limits in the food.Key words: Heavy metals, fish species, water samples, toxicit

Water quality and fish diversity of Federal University of Agriculture Abeokuta reservoir

Federal University of Agriculture reservoir is one of the recently constructed in Abeokuta, Ogun state, Nigeria, therefore the need to assess the water quality, fish diversity and catch assessment of this new water body. Data on fish species were collected on a forthnight basis using multi-stage gillnet sampling techniques for four months (September- December, 2011). Three sampling stations were randomly selected from the entire reservoir. A variety of sampling methods were used at each site in order to reach every fish species. At the river channel and the floodplain sites, traps, cast nets (2.55cm mesh), seine nets (2.55 x 2 cm mesh), monofilament nylon gillnets (15.55 cm mesh), and hook and line were employed. Efforts were made in order to catch fish species in large abundance. Some sampled fish (dead) were collected and placed in cool boxes and examined within 18 hours of capture. Others were preserved in 15% formalin and stored for later examination. A total of 863 fish specimens were caught during the study period. These were identified and classified into 5 species belonging to 3 families. The percentage species composition of the harvest by numbers and weight for all fish species that contributed more than 1% in all the stations combined, were computed. Study of the physico-chemical parameter such as dissolved oxygen ranged from 5.03 to 7.19mg/l; 26 to 280C temperature; 64.8 to 148ppm alkaline; pH 6.67-6.90; 32.5 to 53.5m transparent; 8.86 to 13.72mg/l nitrate; 0.58 to 0.64mg/l phosphate; 0.024 to 0.069 o/oo saline; 103-270cm deep. pH and water temperature serve as variables since the fluctuation of one affects the values of others. The water quality parameters were favourable for fish production. The gillnet fisheries indicated that different mesh sizes of experimental gillnets were sensitive to different fish species. 67.2mm, 78.4mm and 112mm, mesh sizes were efficient in catching Clarias gariepinus, Barbus occidentalis and the Cichlids respectively. The study has shown that middle water was the most suitable habitat for fish in the reservoir. Water level and temperature were observed to guarantee high fish yield in the reservoir.Keywords: Reservoir, Physico-chemical parameters, catch compositio

Assessment of heavy metals concentration in the intestine, kidney and muscle of Oreochromis niloticus in Federal University of Agriculture Abeokuta reservoir

Different sizes of Oreochromis niloticus (Tilapia) were caught using cast net in FUNAAB reservoir. Water samples were also collected and analyzed for five metals: Lead, Chromium, Cadmium, Zinc, and Copper by Atomic Absorption Spectroscopy (AAS). During the experiment, three tissues were compared with the level of metal in water, Intestine, Kidney and Muscles. Generally, lower concentrations of metals were recorded in water than in fish tissues; lower concentration in the tissue of O niloticus except were found in the water which is less than the recommendation for human consumption by World Health Organisation. Lead was found to be the dominant in the intestine of Oreochromis niloticus while Chromium was recorded the least of all the metals. There is a significant difference (P<0.05) in heavy metal concentration in the tissue of O niloticus except for Chromium. Though, the heavy metals of interest were present in a measurable quantities, they are still within safe limits for consumption.Keywords: Heavy metals, concentration, Oreochromis niloticus, reservoir, FUNAA

ENDO AND ECTO PARASITE PREVALENCE AND ABUNDANCE IN SOME FISH SPECIES FROM AKOMOJE, OGUN RIVER SOUTH-WEST NIGERIA

Parasites are the second most abundant microorganisms that infect and cause disease in wild and cultured fish after bacteria. The study investigated the parasite prevalence, abundance, mean intensity and dominance in some fresh water fish from Akomoje, Ogun River, Nigeria from February to May, 2016. Eight fish species were collected and identified to the species level. Experimental fish were measured and weighed. Endo- and ecto-parasites were examined for; from Skin/scale, dorsal and caudal fins, gills, intestine and stomach of fish. Water sample was collected from shore, mid and extreme of the landing site and also analysed for parasite abundance. Prevalence of parasite in all fish species varied slightly with size. Myxozoan group revealed the highest dominance of ecto- and endo-parasites in virtually all fish species while mean intensity and abundance of Myxozoan spp. was highest in Oreochromis niloticus and Hemichromis fasciatus. Highest case of a single species of ecto- and endo-parasite in a fish sample was that of Nematode larva in Chrysicthys nigrodigitatus (41.43 %) and Trichocerca sp. (Rotifera) in Mormyrus rume (52.9 %).Water analysis revealed three parasite groups that were present in the sampled fish. Conclusively, Akomoje landing site of Ogun River has a rich burden of parasites