Physico-Chemical Parameters and Ichthyofauna Composition of Oyan Dam Area, Ogun State, Nigeria
Abstract
The surface water physico-chemical characteristics and ichthyofaunal composition of Oyan Dam and its environment were investigated monthly between December, 2017 and August, 2018. The surface water temperature, pH, Total Dissolved Solids (TDS) were measured in-situ with a portable Hanna TDS/pH meter - (HI9813-6). The Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Phosphate, Nitrate, and Nitrite were determined in the laboratory using standard methods. The monthly total rainfall, relative humidity, and air temperatures were obtained from world weather online/Abeokuta weather. Fish abundance (ichthyofaunal composition) was determined by monitoring and recording the catch from fishermen. The pH ranged between 6.9-8.2, 7.2-8.3, and 7.0-8.2 in Apojola, Dam site, and Ibaro respectively. Highest DO 7.86 mgL-1 and lowest 4.2 mgL-1 were recorded in the Dam site in April and July. Eighteen fish species belonging to ten families were encountered in the study. The family Cichlidae contains more fish species than any other family. Ichthyofauna species recorded were Oreochromis niloticus, Tilapia guineensis, Sarotherondon galilaeus, Tilapia mariae, Tilapia zillii, Chrysichthys nigrodigitatus, Sarotherondon melanotheron. Chrysichthys nigrodigitatus was the most abundant (16%) and occurred throughout the sampling period. The least abundant species (0.05%) Parachanna obscura, occurred only in December and January. The study revealed that Bagridae represented by Chrysichthys nigrodigitatus contributed to the highest number of fish. The physico-chemical parameters are within the range for culturable species. Nigeria can derive a substantial proportion of its fish demand from the Oyan Dam, if private and public sectors were allowed to culture fish in the dam.
Copyright (c) 2020 Adesola O. Osibona, Simeon O. Ayoola
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