The joint action effects of the binary mixtures of some botanical piscicides on post juvenile Clarias gariepinus

Botanical piscicides over the years have been used singly in fishing efforts. This research investigated the joint action of binary mixtures of Carica papaya + Nicotiana tabacum, Anacardium occidentale + Senna occidentalis, and A. occidentale + Luffa cylindrica. Relative toxic units (RTU) estimations and synergistic ratio (SR) models were used in the joint action evaluation. The 96 h LC50 (95% confidence limit [CL]) results revealed that the mixture of C. papaya and N. tabacum showed antagonism (reduction in toxicity) in both predetermined mixture ratio 1:1 and equitoxic mixture ratio 1:2. The RTU value for mixture ratio 1:1 was 0.298, while SR was 0.221. The mixture ratio 1:2 had RTU of 0.421 and SR of 0.384. The mixture of A. occidentale and S. occidentalis also followed the antagonistic model with mixture ratio 1:1, having RTU of 0.927 and SR of 0.577, while the mixture ratio 1:2 had RTU of 0.489 and SR of 0.360. The mixture ratio 1:1 of A. occidentale and L. cylindrica was synergistic with RTU of 2.145 and SR of 1.442. Most of the binary mixtures of the botanical piscicides were antagonistic.   Key words: Joint action, binary mixtures, botanical piscicides, Clarias gariepinus.