Argulus is an ectoparasite that frequently infects goldfish, with severe effects and a high death rate. The use of plant extracts has been widely reported to have antiparasitic activities, including one of the solasodine compounds in sour eggplant extracts. This research evaluated the antiparasitic activities of Compositions A (Solanum ferox and Zingiber zerumbet extract at 400 and 200 ppm, respectively), B (SFE and Boesenbergia pandurata at 900 ppm), and C (single Solanum ferox at 400 ppm). The research stages comprised 1) isolation and analysis of solasodine content in sour eggplant extracts and its extract composition, 2) in vitro antiparasitic activities on Argulus sp. at doses of 50 and 100 ppm with a testing time of 60–240 minutes, and 3) in vivo antiparasitic activities on Argulus sp. on goldfish at a dose of 100 ppm and observation for 2–12 hours of medication. The results showed that sour eggplant extracts had a solasodine concentration of 7.151 mg/L, whereas the derivative compositions A, B, and C were 656, 485, and 295 ppm, respectively. The in vitro testing demonstrated that composition A was effective for killing approximately 80–100% of Argulus, whereas compositions B and C killed 80–90% and 60–70%, respectively. Viewed from the effectiveness for killing parasites, the result was excellent (above 50%). The in vivo medication test was continued using three extract compositions at a dose of 100 ppm. Compositions A, B, and C were found to be capable of releasing 81.33, 75.67, and 71.00 arguli, respectively, per fish. We concluded that the single SFE extract and a concoction with BPE and ZZE had reasonable antiparasitic activity, whereas the concoction of SFE and ZZE killed more Argulus parasites at a higher rate.