The soy sauce containers were added on Monday to the list of prohibited single-use plastic products, which also include disposable straws.
The state authorities claim that fish-shaped soy sauce bottles, which usually hold 2 to 3 millilitres and are often discarded rather than recycled, contribute to ocean pollution.
The authorities also said the bottles pose a risk to wild animals, which may mistake them for food.
"Single-use plastics are often used for seconds, but they last a lifetime in our natural environment," Susan Close, environment minister for South Australia, said in a statement.
The authorities have instructed food companies and restaurants to provide refillable bottles on tables and to replace takeaway bottles with small pouches or other containers.
Fish-shaped soy sauce containers were invented in the 1950s by Japanese entrepreneur Teruo Watanabe, who founded Asahi Sogyo Co., a food-related materials maker based in the western Japan prefecture of Osaka. Their use spread as Japanese food became popular abroad.
[Copyright The Jiji Press, Ltd.]