Lightsticks baits are discharged into the ocean after their use in longline fishing. The traditional Brazilian community of Costa dos Coqueiros, Bahia, uses lightsticks as a medicine for rheumatism, vitiligo, and mycoses. It may affect marine life when its content leak into the ocean. This study assessed the toxicity identification and evaluation (TIE) of lightsticks constituents on marine mysids Promysis atlantica. The internal solution was dissolved in seawater with ethanol. The lethal concentration of the contaminant that causes mortality in 50% of the exposed population (LC50) after 3h was 0.001%, demonstrating that lightstick is exceptionally toxic because low concentrations cause mortality to mysids P. atlantica. Due to lightsticks' high toxicity, the TIE baseline was 0.005% SSE (stock solution ethanol), and the selected endpoints were behavior and lethality. The sample submitted to aeration presented a significant reduction (P < 0.05) in toxicity (0.005% SSE) because the volatile compounds caused the toxic effect. The sodium thiosulfate treatment induced an insignificant decrease in toxicity. Thus, a new assay was conducted considering aeration and sodium thiosulfate. This combination reduced lightstick toxicity compared to the baseline lightstick, suggesting that volatile compounds and oxidants were responsible for toxicity; even in low concentrations, lightstick can promote significant behavior changes and deleterious effects. It is recommended to create new mechanisms to inspect fishing vessels, thus avoiding the improper disposal of attractors at sea and common garbage.