They might look pretty – or at least, pretty harmless, but Australia's ornamental fish trade can pose a serious threat to our waterways. Once an invasive is established, it makes eradication almost impossible, which means prevention is always better than cure.

In this episode we're joined by freshwater fish biologist Mariah Millington to find out exactly what impact ornamental fish are having on our native species, as well as what we can do to encourage responsible fish ownership.