Inhibition of Growth and Nutrient Digestibility in the Cichlid, Tilapia zilli (L.) Exposed to used Automobile Lubricating

Abstract

Fingerlings of the cichlid, Tilapia zilli (mean weight: 7.15 ± 0.01 g) were exposed to the following sublethal concentrations of water soluble fractions (WSFs) of used automobile lubricating oil: 125.00, 62.50, 31.25, 15.63, 7.81 and 0.00 mL/L. The exposure period was 10 weeks under laboratory conditions. There was no mortality in the exposed fish throughout the exposure period, but results obtained showed that growth and nutrient digestibility of the exposed fish were significantly reduced with increase in the WSFs concentrations. Groups of the fish exposed to 15.63 mL/L and above recorded negative specific growth rate (SGR) values. Similarly, protein and carbohydrate were poorly utilised in the groups exposed to 15.63 mL/L and above. The implications of used automobile lubricating oil as it affects growth and nutrient digestibility by fish in polluted aquatic environment are discussed.


Journal of Aquatic Sciences Volume 16, April 2001, pp. 25-28



KEY WORDS:

Growth, nutrient digestibility, cichlid, Tilapia zilli, automobile lubricating oil.