Abstract This work focused on the histological alterations in gill, liver and kidney of fish Colossoma macropomum exposed to different temperatures (18 °C, 29 °C, 35 °C) with 10 mg/L of herbicide Paraquat (PQ), during 21 days. The fish exhibited histopathological changes in these tissues; the most important alteration in gills was telangiectasis. Liver showed debris accumulation inside cytoplasm hepatocytes, karyolysis, karyohesis and a decrease in the size of sinusoids. Hyperplasia of melanomacrophagic centers (MMC) and an increase in basophils were observed in kidney. The lesion inducing by PQ and the damage in tissue depended of temperature exposure fish. The severity of lesions clearly differed among organs with the liver showing the most extensive damages followed in order by the kidney and gills. In PQ/18 °C group it was observed the changes in the pattern of lesions, with kidney showing higher damage followed gills and liver.