Spirulina sp. is one of the potential microalgae as a source of protein because it contains 100% vegetable protein. Fisheries industry wastewater contains a lot of protein and fat, resulting in quite high values, nitrates and ammonia. Fish waste can be used as raw material for organic fertilizer microalgae that can grow in waste besides producing biomass and can reduce the burden of pollution. In this case, researchers want to know the growth rate of microalgae Spirulina sp. in the media of liquid waste resulting from fish handling from Cemara Market, Medan, North Sumatra. This research was conducted experimentally, the research design used was a Completely Randomized Design (CRD) consisting of five treatments with three replications with different waste concentrations with a volume of 1000 ml. Based on the Anova test results show that there is a real influence of the variation of treatment on the growth of Spirulina sp. with a significance value of 0.000 (p <0.05). Also supported by the results of Duncan’s further tests which showed that treatment A (30% waste) and treatment K (control) were significantly different from each other and also had a significant effect on treatment B (60% waste).