New Zealand scientists have made a breakthrough in the battle against the noxious pest sometimes known as "rock snot".
In a world first, researchers at the Cawthron Institute in Nelson have bred the invasive alga, Didymo, in the laboratory.
The scientist say it took four years of research and will allow them to more accurately identify which conditions promote and which deter blooms of Didymo.
The achievement follows news last week that Didymo has spread west of Fiordland.
Using the lab-grown samples, researchers have already discovered some chemicals and bacteria can prevent Didymo attaching to rocks - which could be used to manage the spread of the pest.
However, they say it will probably never be completely eradicated.