The freshwater lake in Bogor Botanical Gardens conservation area is home to the Lasia spinosa plant, which belongs to a member of the Araceae family with a freshwater habitat. This plant is popular in Bangladesh and employed in Ayurveda as an anti-rheumatic and anti-inflammatory agent. Previous research demonstrated its antioxidant properties. This study seeks to identify toxic compounds in three types of L. spinosa extract using the Brine Shrimp Lethality Test (BSLT) using A. fransiscana shrimp larvae, so they can be developed into cytotoxic and anticancer agents. The phytochemical analysis of L. spinosa extract revealed the presence of alkaloids, phenols, flavonoids, tannins, saponins, mono- and sesquiterpenes. The LC50 values for methanol, ethyl acetate, and n-hexane extracts were 144.87 µg/mL (strong toxicity), 52.95 µg/mL (strong toxicity), and 286.94 µg/mL (weak toxicity), respectively.