A male red shiner fish. (Wikimedia Commons/Marine Discovery/HO)

Dr. Jessica Ward from the University of Minnesota looked specifically at blacktail shiner and red shiner fish. Researchers took fish from both species from streams in Georgia and kept them in separate tanks for 14 days. Some of the tanks contained BPA.

On the 15th day, the fish were introduced to each other.

The researchers recorded any changes to the fish, including colour and behavioural differences, such as mate choice.

BPA, the study noted, disrupts a fish's endocrine system, which controls the release of hormones. This can impact behaviour and appearance.

"Our research shows how the presence of these manmade chemicals leads to a greater likelihood of hybridization between species," Ward said in the study, released Wednesday in the journal Evolutionary Applications. "This can have severe ecological and evolutionary consequences, including the potential for the decline of our native species."