A new study says a chemical commonly found in soap products may be affecting the ability of fish to protect themselves from predators.
The study by Dr Ashley Ward, from the University of Sydney, has been published in Proceedings of the Royal Society B.
It examined how fish are effected by the chemical nonylphenol, a soap ingredient which is commonly found in rivers and marine estuaries.
Dr Ward says the chemical could be preventing fish from forming shoals with other fish.
"It seems to be blocking their ability to communicate chemically, so this prevents them from recognising potential shoalmates and recognising other fish, potentially also other fish to avoid," he said.
"Obviously this could have serious impacts on their ability to survive and thrive in their environment."
This is not the only thing nonylphenols are doing to fish. They are also endocrine disrupters, and can inhibit a fishes ability to sexually develop properly. These nonylphenols act as estrogens and prevent the successful development of male fish, essentially having the potential to make a local population "female."