Influence of antinomy potassium tartrate on fish, planktonic crustacea, and green algae were studied in laboratory experiments. Test aquatic species were Oryzias latipes, Moina macrocopa, S. mixtus, and Pseudokirchneriella subcapitata. Survival rate of Oryzias latipes larvae were reduced in the presence of antimony. The effect on early life stage development of Oryzias latipes has not significant effect upon antimony contamination in water, although some embryos showed the developmental abnormalities. Moina macrocopa and S. mixtus were much more sensitive to antimony than Oryzias latipes, indicating that planktonic crustacea could be a better indicator for antimony pollution. S. mixtus was most sensitive to antimony.