Table 1.
Half-lethal concentration (LC50) of Chlorpyrifos (CPF) in female African catfish, Clarias gariepinus.
| CPF Concentration (µg/L) | No. of Fish/Concentration | No. of Alive Fish |
No. of Dead Fish |
a | b | a × b |
|---|---|---|---|---|---|---|
| 0.00 | 8 | 8 | 0 | 0.0 | 0.0 | 0.00 |
| 25.00 | 8 | 6 | 2 | 25 | 1.00 | 25 |
| 50.00 | 8 | 4 | 4 | 25 | 3.00 | 75 |
| 100.00 | 8 | 2 | 6 | 50 | 5.00 | 250 |
| 200.00 | 8 | 1 | 7 | 100 | 6.50 | 650 |
| 400.00 | 8 | 0 | 8 | 200 | 7.50 | 1500 |
| ∑ a × b = | 2500 | |||||
Half-lethal concentration (LC50) of chlorpyrifos = the highest concentration − ∑a × b/n; a: constant factor of difference between groups; b: mean value of dead fish between every two successive groups; and n: number of fish in each group.