The effects of clomazone (0.5 and 1.0 mg/L) according to nominal concentrations used in paddy rice fields (0.4-0.7 mg/L) on protein and carbohydrate metabolism and haematological parameters were evaluated in silver catfish (Rhamdia quelen) after 12, 24, 48, 96 and 192 h of exposure with a recovery period of 96 and 192 h. Liver glycogen increased significantly (P<0.05) in all periods and concentrations tested. The maximum glycogen increase reaches 250% after 12h of exposure. Muscle glycogen reduced significantly after 24, 48, 96 and 192 h for both clomazone concentrations (P<0.05). Significantly elevated plasma glucose values (P<0.05) and variation in glucose in the liver and muscle of exposed fish were observed. Muscle lactate levels increased after 12, 24 and 48 h of clomazone exposure (22-67%), but reduced in the liver (P<0.05). Protein levels were enhanced in the liver and white muscle, except at 96 and 192 h of exposure, whereas it increased in the plasma in the period from 48 to 96 h (P<0.05). Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly elevated in the plasma (P<0.05). In the liver, ALT increased after 24 h, while AST activity was enhanced only after 12 h of exposure. Hematocrit contents were reduced after 96 and 192 h of exposure. Most of the metabolic disorders observed did not persist after the recovery period, except for the liver AST and ALT activity. Clomazone concentrations used in this study appear safe to fish, Rhamdia quelen, because overall parameters can be recovered after 96 and 192 h in clean water. ALT and AST activity may be an early biomarker of clomazone toxicity.