Chlorella vulgaris can utilize organic substances contained in waste rubber which serves as a medium for its growth. C. vulgaris is one of the types of microalgae that can be used as raw material forage and natural forage fish. This research aims to utilize crumb rubber industry wastewater as a medium for the growth of C. vulgaris natural forage fish. The initial phase of the research, namely the preparation of pure isolates of C. vulgaris, followed by the rejuvenation to log phase, carried out to scale up biomass obtained from cultures of C. vulgaris which could be used as a natural forage. The next was testing the quality of natural forage product including beta carotene, folic acid, oils and fats, fat, unsaturated fat, protein, moisture content, ash content, chlorophyll, crude fiber, iron (Fe), manganese (Mn), potassium and vitamin and the wasted residual of the media used. The results of the test for protein content and moisture content of C. vulgaris fish forage by utilizing the waste water of crumb rubber industry respectively were 2.3% and 95.46%. While the quality of the natural forage product produced were unsaturated fatty 0.44 mg / kg; 2.3% protein; fatty oils 141 mg / L; chlorophyll a 2.7094 mg / L; chlorophyll b, 0.8424 mg / L and vitamin B1 3.99 mg / kg; Vitamin D 2.52 mg / 100 g and Vitamin E 1.09 mg / 100 g
