Abstract

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.