Lethal effect of water soluble fractions of Forcados crude oil on African catfish, Clarias gariepinus

Abstract

Juvenile and fry Clarias gariepinus (mean weight 13.5 ± 0.48g and 2.13 ± 0.64g respectively) were exposed for 96 hours to different lethal concentrations (1.0 to 15.0mg/L) of water soluble fractions (WSF) of the Forcados crude Oil.  each static tank contained ten fish randomly selected in triplicates.  The fry was more sensitive while the juvenile was more resilient.  The 96-h LC50 value obtained for C. gariepinus fry was 4.0mg/L and for juvenile was 7.4mg/L.  The pulsation counts and opercular beats per minute fluctuated with time and concentration; they increased from initial to a certain level and then decreased to a lethal condition.  The lethal pulsation count at 48^th hour in 15.0mg/L (CGJ) was 38, and in 12.0mg/L (CGF) was 33; sublethal pulsation counts in both CFG and CGJ ranged between 33 and 39 while non-lethal pulsation ranged from 40 counts and above.