The objective of this study was to evaluate the acute toxicity of formalin and its level of therapeutic safety in early stages of Lophiosilurus alexandri. Experiment 1, larvae 7 days after hatching (DAH) were exposed to 43.2, 86.4, 172.8, 345.6, 691.2, 1404.0 mg/L of formalin. Experiment 2, juveniles with 22 DAH exposed to 54, 108, 216, 432, 648 mg/L. Experiment 3, 45 DAH exposed to 86.4, 172.8, 345.6, 691.2, 1036.8 mg/L. The experiments had a control without addition of formalin and all were carried out in duplicate. The LC50-12 h were: Experiment 1 = 108.86 mg/L; 2: 152.74 mg/L; 3: 244.38 mg/L of formalin. The respective safety levels were: Experiment 1 = 66.22 mg/L (1 h), 10.89 mg/L (12 h); 2 = 49.17 mg/L (2 h), 15.27 mg/L (12 h); 3 = 68.89 mg/L (2 h), 24.44 mg/L (12 h). The results showed that the developmental stage influenced the sensitivity of animals to formalin.
Animals Catfishes