Unexpected survival of sharptooth catfish Clarias gariepinus (Burchell 1822) during acute rotenone toxicity trials will complicate management of invasions.
The sharptooth catfish Clarias gariepinus is an emerging global invader for which control strategies might include the use of piscicides such as rotenone. Experimental exposure demonstrated that C. gariepinus was less susceptible to rotenone than most other fish species, with unexpected survival observed at rotenone concentrations of 87.5 and 100 µg L-1. C. gariepinus were also observed exhibiting avoidance behaviour to rotenone treated water and were found to be capable of recovering from rotenone exposure. As such, effective eradication might not be attainable even at a dose exceeding 100 µg L-1 with exposures of longer than 24 h. This exposure scenario may pose an unacceptable risk to non-target fauna and highlights the difficulty associated with managing current and future invasions.