Background: Most industrial toxic effluents and human-made discharges eventually find their way into aquatic ecosystems (No, 2021; OECD, 2024). With rapid global economic development, the large-scale emission of heavy metals has become particularly concerning (Kumar et al., 2018; Shao et al., 2014). The frequent release of these excessive pollutants into water bodies has detrimental effects on aquatic life. To assess fish toxicity, contemporary and standardized acute toxicity tests are frequently employed, proving highly effective in environmental risk assessment. For example, the lethal concentration (LC50) is widely recognized worldwide as a valuable tool for studying environmental toxicology. The test for quantifying the diversified effects of this toxicant is thus immensely essential to maintain the water quality standard and to assume the effects of toxicant to the aquatic organism.

Method: In this study, two ornamental fishes i.e., Pethia, commonly called as rosy barb that belongs to order- cypriniformes and Hyphessobrycon commonly known as Buenos Aires Tetra that belongs to order-characiformes were used as test organisms. They were exposed to different concentrations of lead. Rosy barb was exposed to 250, 275, 300, 325, 350 mg/L of lead and 365, 375, 385, 395 and 405 mg/l in case of tetra along with control in both the species having no metal toxicant and with all the conditions constant.

Results: The 50% lethal concentration (LC50) was 565mg/l after 24h, 525mg/l after 48h and 389mg/l after 72h for Rosy Barb and 380 mg/l after 24h, 355 mg/l after 48h and 347 mg/l after 72h for BA Tetra. Rosy Barb was detected with higher LC50 values and showed higher resistance than BA Tetra. Presence of more keratinized structure and having larger body size than tetras may be the possible cause behind this.

Comparison of Lethal concentration of Lead acetate in Rosy barb (Pethia sp) and Buenos Aires Tetra (Hyphessobrycon sp)