Zebrafish larvae acute toxicity test: A promising alternative to the fish acute toxicity test

Aquatic toxicity is a mandatory component in risk assessment of chemicals. The currently recommended used acute fish toxicity (AFT) test requires a large test system, bringing onerous experimental operation and discharge of much experimental wastewater. In this study, we established a more convenient and efficient test defined as the zebrafish larvae acute toxicity (FLT) test, which employed zebrafish larvae at four days post fertilization as the test organisms and implemented a 48-hour exposure in 6-well plates. Based on validated reproducibility, we applied this test to evaluate the acute toxicity of 35 chemicals. By comparing the results with the existing acute toxicity data reported in the literature, we found that most chemicals exhibited highly positive correlated LC₅₀ in the FLT and the AFT test, with the same or similar toxicity grade. The FLT test showed more comparable sensitivity with the current AFT test than the previously recommended fish embryo acute toxicity test (FET). Moreover, the FLT test is easier to implement than the FET test which requires microscopic observation to identify the fertilization and development status of the embryos. Despite a limitation similar to the FET test in terms of detecting neurotoxicants, the FLT test could be a more promising alternative to the AFT test relative to the FET test.