In this study, the toxicity of smoked and unsmoked filtered cigarette butts of various brands was conducted on Clarias gariepinus. The mean bodyweight of the fish was 4.72g. Leachate of cigarette butts was prepared by soaked 24 smoked (4.21g) and unsmoked (4.82g) cigarette butts in six litres of water for 24 hours. The leachate was serially diluted to obtain concentration of 8 cigarette butts per litre (8CB/L), (6CB/L), (4CB/L), (2CB/L), (1CB/L), (0.5CB/L), (0.25CB/L) and (0CB/L). Two hundred and forty (240) C. gariepinus of 21 days old were randomly exposed to the 8 different concentrations with ten fishes per treatment and replicated 3 times. T1 was exposed to 0CB/L, T2 (0.25CB/L), T3 (0.5CB/L), T4 (1CB/L), T5 (2CB/L), T6 (4CB/L), T7 (6CB/L) and T8 (8CB/L). The experiment was carried out for 96 hours. The result shows that the mortality of C. gariepinus increased with an increase in concentrations of the cigarette butts and time of exposure. Table 1 shows that there was 100% mortality in T8, T7 and 36.7, 33.3, 16.7, 13.3, and 6.7% mortality was observed in T6, T5, T4, T3, and T2 respectively after 96 hours of exposure while there was no mortality in the control treatment (T1). Table 2 shows the results of LC50 and LC 95. LC50 value of 0.57 and LC95 value of 2.30 were obtained after 96 hours of exposure. The result of the physico -chemical water quality shows that there was no significant difference (p>0.05) in the mean temperature, dissolved oxygen and salinity of the leachate but there was a significant difference (p<0.05) in the mean pH among the treatments. This study shows that cigarette butts leachate is toxic to freshwater fish.