Pollution is caused by dangerous heavy metal such as Pb, Cu and Zn are toxic in the body tissues of organisms such as fish in high concentrations, it will be harmful to human health The purpose is to create an eco-friendly fish preservative tool with cooling system of thermodynamics and photocatalytic Co doped ZnO nanoparticles. this device can reach temperature 15 o C. Then to reduce dangerous heavy metals and kill bacteria used principle of photocatalytic Co doped ZnO nanoparticles. Co doped ZnO synthesized by sol-gel method. Then proceeded to spray coating and drying with furnace. The result is a purple clear homogeneous solution. From the analysis of the obtained bandgap Co doped ZnO about 2.28 eV and from SEM generated that average particle size Co doped ZnO is 60 nm. From the result of Co doped ZnO can be initiated by visible light and may have antibacterial activity so that this material can be made as a tool to prevent the growth of microorganisms only using regular light Key words : Eco-friendly fish preservative tools; less energy based on cooling dynamic; Nano Co Doped ZnO.