Per- and polyfluoroalkyl substances (PFAS) are a novel group of synthetic chemicals that are widely used in household and industrial products. PFAS are known to be environmentally persistent, characterized by having longer biological half-lives due to their carbon backbone with fluorine atoms. Perfluorononanoic acid (PFNA, C9HF17O2) is an example of a long-chain perfluorocarboxylic acid. As the potential toxicity of several long-chain per-and polyfluoroalkyl substances (PFAS) on aquatic species is not well understood, we assessed the effects of long-chain PFNA exposure on developing zebrafish. Several zebrafish embryos/larvae were exposed to PFNA over a 7-day period post-fertilization. Upon exposure termination, we measured sublethal toxicity effects in relation to locomotor behavior, apoptosis levels, neurotoxicity, oxidative stress (ROS), hatch rate, deformity rate, and survival rate. There was no evidence for ROS induction in 7-day-old larvae fish exposed from 0.1-1000 μg/L. In regard to developmental endpoints, PFNA did not significantly affect the hatch, survival, and deformity rate in comparison to the controls at the concentrations tested. However, PFNA induced hypoactivity of zebrafish larvae at concentrations of 0.1,10, and 1000 μg/L. PFNA was also observed to increase apoptosis in the 0.1 μg/L concentration. PFNA did not have any effect on transcript levels of genes related to apoptosis and neurotoxicity. As such, RNA-seq is being conducted to elucidate potential mechanisms of toxicity and this will be discussed. These data further our understanding of sublethal toxicity data for PFNA in zebrafish, helping to further contribute to toxicological risk assessments for PFAS