Abstract: Investigations were carried to assess the sublethal effects of a herbicide clincher (100 EC) containing cyhalofop butyl 100 g ( a.i )·L-1 as the active ingredient and the insecticide profurite aminium 78% SP, 780 g ( a.i )·kg-1 on liver esterases and hepatic glutathione S transferase (GST) in goldfish ( Carassius auratus ) and topmouth gudgeon ( Pseudorasbora parva ). GST was found to be induced in both goldfish and topmouth gudgeon by the profurite aminium at concentration of 0.234 mg·L-1 . Clincher both at concentration of 1 and 2 mg·L-1 caused GST induction in topmouth gudgeon. The mixture of clincher and profurite aminium had the highest effect in topmouth gudgeon 722.3 nmol·(min -1 ·mg-1 protein) with a possible indication of additive toxicity. Liver esterases were induced by both clincher (1 and 2 mg·L-1 )and profurite aminium (0.117 and 0.234 mg·L-1 ) in goldfish. In topmouth gudgeon liver esterases were induced by profurite aminium but inhibited by clincher. It is suggested that the two biotransformation enzymes may be directly or indirectly affected by the tested chemicals and that there are differences between them.