The bioaccumulation and toxic effects of heavy metals have caused ecological damage to aquatic ecosystem. In this study, concentration of heavy metals including zinc, lead, cadmium, iron, and copper were determined in the sediment and water as well as in the muscle, gill, and intestine of two fish species (Pelmatochromis guentheri and Pelmatochromis pulcher) of Mbaa River in Southeastern Nigeria. Samples were collected at three different spots from the river, and the level of heavy metals specified above were determined by atomic absorption spectroscopy (AAS) after a modified wet digestion process. The results indicated that sediment had the highest concentration of the heavy metals investigated while water had the lowest concentration. Fish tissues showed appreciable bioaccumulation of these metals as evidenced by a higher concentration profile when compared with that of water. Furthermore, the concentration of these heavy metals in water and their bioconcentration factor in the fish were above the recommended limit by WHO and FEPA, indicating that Mbaa River along Inyishi may not be suitable for drinking nor the fish safe for human consumption. The study also reveals the use of fish as bioindicator of aquatic environment.

The Length-Weight relationship of some fish species from Oramiri-Ukwa River, was studied from January to December, 2014. The slope (b) values obtained in the nine species ranged from 1.830 to 5.670 with most of the fishes indicating a negative allometric growth pattern except for Papyrocranus afer, with b value of 3.04, thus showing a positive isometric growth pattern. The following fish species showed a high degree of positive correlation at (P > 0.05); Ctenopoma kingselyae, Alestes imberi, Channa obscura, Oreochromis niloticus, Tilapia mariae, Tilapia zillii, Synodontis omais, and Papyrocranus afer. Chrysichthys auratus did not show this positive correlation. The condition factor (K) of the fish species ranged from 0.99 to 4.54, indicating that most of the fish were in good condition except for Chrysichthys auratus with 0.99.

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This paper review and addresses the major effects of climate change on Aquaculture, whose contributions to agriculture development are quite enormous. To achieve these objectives the status of this sub sector to the total fish supply are therefore analyzed with a view to identifying the major impacts of climate change on aquaculture. Aquaculture not practiced evenly across the globe requires an evaluation of the effects of climate change through the current aquaculture practices in the regions and the different environments. The main elements of climate change that would impact on aquaculture production include sea level and temperature rise, change in monsoon patterns and extreme climatic events and water stress, among others thereby causing varying degrees of concern either positively or negatively or directly or indirectly. Therefore, to ameliorate this adverse effect of climate change on aquaculture in Nigeria, and the world generally, attempts are made to deal with the climate change effects on the different culture systems in order to bring out all the complex attributes of climate change and the possible mitigation strategies for the future control. These will enhance aquaculture production and then claim back the expected role as a major source of animal protein in the future.

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