Use of the Lampricide 3-Trifluoromethyl-4-Nitrophenol (TFM) to Control Tadpoles in Warmwater Ornamental Fish Ponds

Abstract

Abstract Laboratory-based static acute toxicity tests were performed to determine the relative toxicity of TFM to selected species of tadpoles and ornamental fish in soft (mean, 45 mg/L as CaCO3) and hard (mean, 177 mg/L) freshwater. Sensitivity was measured as the 96-h LC50, the concentration lethal to half the test animals in 96 h, The sensitivity of larval bullfrogs Rana catesbeiana to TFM was 1.50 mg/L in soft water and 4.20 mg/L in hard water. The 96-h LC50 of TFM for larval southern toads Bufo terrestris was 0.51 mg/L in soft water and 0.70 mg/L in hard water. Toxicity of TFM (96-h LC50) to the fish tested ranged from 1.02 to 7.73 mg/L in soft water and 1.83 to 18.05 mg/L in hard water. Probit analysis indicated that the amount of TFM required to kill 99% of bullfrog larvae was 3.35 mg/L. A 96-h exposure to 3.35 mg!L TFM would also kill 99% of suckermouth catfish Hypostomus plecostomus, 92% of black neon tetras Hyphessobrycon herbertaxelrodi, 90% of tiger barbs Puntius tetrazona, 50% of freshwater angelfish Pterophyllurn scalare, 25% of dwarf gouramis Colisa lalia, and 5% of southern platyfish Xiphophorus maculatus. Although there was apparent selectivity when used with certain ornamental fish species, the use of TFM as a tadpole control agent can be nonselective, unpredictable, and expensive.