Soil Sediment and Hardness of Water Reduce the Acute Toxicity of Deltamethrin to Scale Carp

Hardness of water and soil sediment were able to reduce the toxicity of deltamethrin significantly scale carp fry. LC₅₀ (96 h) values of deltamethrin, which was 0.102 mg L”‘in soft water increased to 0.8 mg L⁻¹in hard water, further when soil sediment was included r to 2.71 mg L⁻¹. Other two treatments of soil sediments i.e. medium hard water with sediments (96 h LC₅₀,0.989 mg L⁻¹) and very hard water with sediments (96 h LC₅₀, 1.808 mg L⁻¹) were also able to reduce the toxicity of deltamethrin significantly in comparison to their respective water treatments (96 h LC₅₀, 0.396 mg L⁻¹and 0.495 mg L⁻¹, respectively). ET value at 1 mg L⁻¹ had also increased significantly from 5.69 h in soft water to 92.63 h in hard water and further to 301.98 h in hard water and soil sediments treatment. A simple method for determination of acute toxicity test of chemical with soil sediment for fish was described.