Spirulina (Arthrospira platensis) is a Cyanobacterium that can be cultured in catfish rearing wastewater. Spirulina stocking density can affect growth rate, density, and reduction of total nitrogen and phosphate content in catfish rearing wastewater culture media. The purpose of this study was to determine the optimal initial density of Spirulina for the growth of Spirulina cultured in the wast…