Bisphenol A (BPA), used in the manufacturing of various plastic products, is widely distributed in the marine environment and significantly impacts aquatic wildlife. In this study, juvenile false clown anemonefish (Amphiprion ocellaris) was used as a model species for low-dose BPA exposure, and to examine the cytochrome P450 1A gene (cyp1a) as a potential biomarker. Fish were exposed to BPA at a range of concentrations for up to 48 hours. Quantification of BPA in the exposed animals revealed that accumulation was significantly higher in the liver than in the muscle. Therefore, liver tissue was selected for further study. In addition to this, the selection of an appropriate reference gene for quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was investigated. Our results showed that ribosomal protein l8 gene (rp18) was the most stable reference gene, compared to 18S ribosomal RNA gene (18S rRNA) and elongation factor 1α gene (EF-1α). This was used as an internal control in the qRT-PCR experiments. Following exposure to BPA, cpy1a expression significantly increased in a dose- and time-dependent manner: after 24 hours exposure to 50 ng/l BPA, it increased 2.82-fold; and after 12 hours exposure to 100 ng/l BPA, it increased 3.44-fold. A low dose of BPA rapidly induces cyp1a expression in this sentinel species. Thus, cyp1a could be used as a potential biomarker for BPA exposure.