The purpose of this study was to determine the effect of variations in the number of tilapia (Oreochromis nilotics) on the growth of Pagoda mustard (Brassica narinosa) with aquaponic systems. The study used a completely randomized design (RAK) with three treatments and nine replications. The treatment in this study was the difference in the number of fish (40, 60 and 80 fish) used in the aquaponics system. The study was conducted for 45 days, the parameters observed were the number of leaves, total chlorophyll content and wet weight of the mustard mustard plant (Brassica narinosa). The research data were analyzed using the Analysis of Variance test, if it had a significant effect then the analysis was continued with the Duncan Multiple Range Test (DMRT) test. The results of the analysis of variance in the number of leaves and the total chlorophyll content of the Pagoda mustard plant (Brassica narinosa) in this study showed significant results (P<0.05), the wet weight obtained a significance of 0.077 (P>0.05). It can be concluded that variations in the number of tilapia affect the number of leaves and total chlorophyll content, but have no effect on the wet weight of Pagoda mustard greens (Brassica narinosa). The results of the Duncan Multiple Range Test (DMRT) showed that the number of tilapia fish had the most effect on the number of leaves and total chlorophyll.   Keywords: Aquaponics, Tilapia, Mustard Pagoda, Growth.