The Response of Fresh Water Fish Syndontisclarias Juveniles to Varied Zinc Sulphide Concentrations Obtained from the River Benueat Makurdi, Benue State Nigeria

Zinc is one of the heavy metals that is common in the Earth's crust. This metal gets into the environment through manmade and natural ways. In this study, standard solutions of zinc sulphide were prepared and exposed to Synodontisclarias juveniles, A fresh water fish obtained from River Benue at Makurdi during its season in 2017. The standard solutions were: 0.5, 1.0, 1.5, 2.0 and 2.5mg/L and the exposure period was acute within 96 hours under laboratory condition in the bowls containing 80 litres with 20 individual members in each of the bowl's concentration after the successful climitasation of the fish. Although the metal is nutritional essential at trace concentration in the body of organism of animals but toxic at elevated concentrations, which informed the need for this study and due its abundance in the Earth's crust. The results of the study depict a change in the body colour of the fish, change in its shape, abnormal swimming and death of fish at the exposure to the elevated concentration during the time of the study. The LC50 was recorded at 1.00mg/L with the death of half members of the fresh water fish exposed to the toxicant, zinc sulphide for four days study period. However, no death was recorded in the bowl without the toxicant concentration indicating that the death rate was due to the toxic effects of the zinc sulphide to the fish. There was increased in the death of the fish from the lowest to the highest concentration of the zinc sulphide on the fish of 40 and 90% respectively during the exposure time. Thus, indicating that the higher the concentration of the metal the more toxic it is. This is irrespective of its nutritional value of the metal in the body of organism and can be transferred through food chain with man been the most affected hence the fish is widely consumed by man. There was a strong relationship between the metal and the death of the fish with R2 value of 0.8754. Consequently, the probit transformed mortality of the toxicant have an R2 value of 0.6562, while the log transformed concentration death rate with the fish was weak with R2 value of 0.1575. This may be due to the low values of the log transformed metal concentration. The water quality in which the fish were exposed with the toxicant were affected with at varied concentrations with mean values of 4.71±0.79mg/L, 463.70±91.93µS/cm, 233.33±35.41mg/L, 7.46±0.20 and 25.08±0.60 0C of DO, conductivity, TDS, pH and water temperature respectively. The t-test at 5% was significant across all the concentration during the time of exposure of the fish. The study concludes that zinc at elevated concentrations is detrimental to the fish and human health and therefore recommended for routine monitoring of zinc in the aquatic environment due its abundance in the earth's crust and the high risk of washing into the waters sources and taken up by the fish.