Rainbow trout were exposed chronically (28-d) through the diet to 0.05 µg/g of two benzotriazole UV stabilizers: 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV-234 CAS# 70321-86-7) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328 CAS# 25973-55-1), alone and in mixture. Liver transcriptome was analyzed by RNA-sequencing at the end of exposure to measure differential gene expression and identify potential biological effects and modes of action of each substance alone and potential synergistic effects in mixture.