The study was carried out on the alga Chlorella vulgaris and young specimens of crucian carp Carassius carassius. The algae and fish were exposed to a pesticide gamametox powder containing 0.6% of lindane and 3% of methoxychlor. Gas chromatography method was used to determine the content of these two active substances in the material. Based on the mean lindane and methoxychlor contents it was revealed that they were bioaccumulated at different levels of the trophic chain. Their accumulation was higher in fish than in algae, which were the source of their food. Their concentration in the muscles of crucian carp was higher when absorbed from food (i.e. Chlorella vulgaris cells), than directly from water. A similar situation was observed in relation to lindane content in the liver. In the brain, however, the concentration of both pesticides was diversioned or similar. The highest concentrations were revealed in the brain of crucian carp, slightly lower in the liver and the lowest in the muscles, i.e. edible parts of fish, irrespective of the way of absorption.