RESUMO
Aiming to test the capacity of retention of carotenoids in tissues, Lophiosilurus alexandri juveniles were fed diets containing 0, 25, 50, 100, 200, and 400 mg/kg of synthetic astaxanthin for 62 days. The inclusion of astaxanthin did not result in significant differences in growth, weight gain, apparent feed conversion, and feed efficiency of the fish. Blood biochemistry and liver histology did not change with the different treatments. At the level of 100 mg/kg of inclusion, there were the highest levels of carotenoids in the blood, and muscle and the smallest difference between the muscle x integument ratio.
RESUMO
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, 1404.0â¯mg/L of formalin. Experiment 2, juveniles with 22 DAH exposed to 54, 108, 216, 432, 648â¯mg/L. Experiment 3, 45 DAH exposed to 86.4, 172.8, 345.6, 691.2, 1036.8â¯mg/L. The experiments had a control without addition of formalin and all were carried out in duplicate. The LC50-12â¯h were: Experiment 1â¯=â¯108.86â¯mg/L; 2: 152.74â¯mg/L; 3: 244.38â¯mg/L of formalin. The respective safety levels were: Experiment 1â¯=â¯66.22â¯mg/L (1â¯h), 10.89â¯mg/L (12â¯h); 2â¯=â¯49.17â¯mg/L (2â¯h), 15.27â¯mg/L (12â¯h); 3â¯=â¯68.89â¯mg/L (2â¯h), 24.44â¯mg/L (12â¯h). The results showed that the developmental stage influenced the sensitivity of animals to formalin.