Evaluation of Iron Toxicity in the Tropical Fish Leporinus friderici

Abstract

The present study aimed to determine the toxicity of iron ions (Fe2+ and Fe3+) in juveniles of “piau” (Leporinus friderici), by means of acute toxicity tests, observation of the opercular beat and hematology. We used 88 specimens of L. friderici divided into 11 treatments: control; 1 mg/L; 3 mg/L; 7.5 mg/L; 15 mg/L and 30 mg/L of Fe2+ and Fe3+ ions, obtained from buffered solutions. Biometric and physiological parameters of fish (0-96 h after intoxication), opercular beating for one minute in the first hour of exposure and blood parameters were evaluated. The results indicate a variability of the toxic effects, the two iron ions were toxic to “piau”, since both in the concentration of 30 mg/L, were 100% lethal to the exposed organisms. Fe3+ caused total lethality also at concentrations of 15 mg/L and 7.5 mg/L. At the concentration of 1 mg/L and 3 mg/L Fe3+, the fish were tolerant and no mortality occurred. At concentrations of 1 mg/L; 3 mg/L; 7.5 mg/L and 15 mg/L, Fe2+ also showed no mortality, decreased glutathione levels (GSH), and increased levels of hemoglobin and methaemoglobin in both groups, with higher changes in Fe3+ groups in relation to hemoglobin and methaemoglobin. Observable changes in GSH levels occurred in animals exposed to Fe2+. The two iron ions (Fe2+ and Fe3+) were very toxic to the “piau” juveniles