MARIOARA NICULA, NICOLAE PACALA, LAVINIA STEF, IOAN PET, ISIDORA RADULOV, TIBERIU IANCU, MIRELA AHMADI, DOREL DRONCA, ADRIANA GHERBON SYNERGIC AND ANTAGONISTIC ACTION OF ACTIVE PRINCIPLES ON CHROMIUM-LEAD ANTAGONISM - IN VIVO EXPERIMENTS Heavy metal pollution of the aquatic environment has become a major concern for the world. As natural water pollutants, heavy metals are among the most toxic due to their cumulative effect and the difficulty of being converted into insoluble compounds in the surface waters. Lead and its compounds are toxic to aquatic organisms, especially fish, even at low concentrations, being able to replace essential elements from the organism. Thus, we tested the concentration of chromium in tissues of Prussian carp’s fingerlings, exposed to chronic lead intoxication, following the synergic and antagonistic effects of some active principles from garlic and chlorella in various tissues. Our experiment was performed on 120 Prussian carps for 21-days as following: C group (without treatment), E1 group (75 ppm Pb into water as Pb(NO3)2 x ½H2O), E2 group (75 ppm Pb into water+2% freeze dried garlic in feed), E3 group (75 ppm Pb into water + 2% freeze-dried chlorella in feed). At the end of the experimental period, tissue samples (gills, muscle, heart, skin and scales, intestine, liver, brain, gonads, and kidney) were sampled after anaesthesia. Atomic Absorption Spectrometry was used to determination of chromium concentrations in tissues. Our results revealed that freeze-dried garlic presented antagonistic effect between administrated lead and tested chromium concentration, while the chlorella showed antagonistic and synergic action, depending on the organ tissue that we had analysed.