Ecotoxicity, hematological and biochemical aspects and effectiveness of antibiotics and ectoparasiticides in juvenile of the pacu (Piaractus mesopotamicus)

Abstract

The bacteria gram negative and the ectoparasites are the pathogens most common in the aquaculture and can manifest in interaction in the farming fish. The antibiotics enrofloxacine (EF) and florfenicol (FFC) can be used for the treatment of bacterioses and the ectoparasiticides thiamethoxan (TH) and toltrazuril (TOL) are pharmochemicals with therapeutic potential for use in the aquaculture. So, the objectives this research will be: 1) estimate the lethal concentration 50% (LC50;48h) of the EF; FFC; TOL and of the TH to pacu (Piaractus mesopotamicus); 2) determinate the effective concentration of EF and TOL in the control of Aeromonas hydrophila and Ictiophitirius multifiliis and of FFC and TH in the control of A. hydrophila and monogenetic in pacu and 3) evaluate the histopathological, hematological and biochemical of the blood before and after the treatment. For the acute toxicity tests the animals (weight between 0,5 e 1,0 g) will be exposed to differents concentrations of each pharmochemical and one control. For the efficacy tests, the fish will be kept in bad conditions (decrease of oxygen, without food, capture and excess organic matter), for development of parasites and after will be infected with the bacteria. After of the manifestation of the clinic signs, will start the treatment with one concentration of each pharmochemical, one control without infection and one with infection. In the end of the experiment will be quantified the fish survivors and the number of parasites. Will be collected samples of blood for hematological and biochemical analysis and the samples of gills, liver, skin and kidney for histopathological analysis. (AU)