The aim of the present work was to investigate the response of zebrafish to the effects of widely-used organophosphates roundup and chlorpyrifos and putative effectiveness of chlorella in terms of decreasing pesticides toxicity. Studied organophosphate pesticide roundup and chlorpyrifos in ecologically relevant concentrations, both individually and in a mixture, evoked the prominent suppression of catalase and total antioxidant capacity in the liver of Danio rerio which were consistent with higher levels of lipid peroxidation, protein carbonylation, and DNA strand break. Also, both roundup and chlorpyrifos provoked endocrine disorders registered as induction of vitellogenin and depletion of triiodothyronine and neurotoxicity appeared as inhibition of acetylcholinesterase after individual action or activation after combined action. The rate of apoptosis observed by caspase 3 activity was decreased, but in different manner depends on the exposure. The potency of toxicity followed the order: roundup > chlorpyrifos > roundup + chlorpyrifos (due to some kind of antagonistic action between chlorpyrifos and roundup in the binary mixture). Based on the results of CART analysis triiodothyronine, TBARS and caspase 3 were determined as the most significant indices for discrimination of the studied groups. The introduction of Chlorella vulgaris in the amount of about 100 thousand cells L-1 into the environment did not show a significant bioremediation effect on the harmful effect of studied pesticides for Danio rerio, which does not exclude the positive impact of algae on the functioning of the ecosystem as a whole and requires further comprehensive research.