The herbicides are chemical substances used to destroy the dark weeds in agriculture (they represent 70% of pesticides) in water, in the embankments of the railway lines in the industrial areas and they are used in small amounts in forest, in wild habitats and in meadows.

Pendigan 330 EC is a herbicide from the group of toluidines which has the aspect of a clear, homogenous, flexible, yellow-brown liquid with a specific smell (aromatic) used to combat the annual monocotyledonous dark weeds and some annual dycotiledonous dark weeds from the sunflower, corn and vegetable crops (Matolcsy et al., 1988).

In this study we analysed the effects of the concentrations of the Pendigan 330 EC (0,002 ml Pendigan 330 EC/l water, 0,004 ml Pendigan 330 EC/l water, 0,008 ml Pendigan 330 EC/l water) herbicide over some physiological indices of Prussian carp (Carassius gibelio Bloch, 1782).

The inhibitor action of the herbicide Pendigan 330 EC manifested for the duration of the experiments over all physiological studied indices (oxygen consumption, respiratory rate, number of erythrocytes), the toxic effect being worse in the case of the experimental variations realized at room temperature 18-20°C compared to those realized at the temperature 6-8°C.