Tasty, versatile, and rich in essential omega-3 fatty acids: salmon is one of the most popular edible fish of all. Shops sell fish caught in the wild, but their main produce is salmon from breeding farms which can pollute rivers, lakes and oceans. Just how big is the problem? German and Chilean scientists are working to answer this question under the leadership of the Helmholtz Centre for Environmental Research (UFZ). They examined the dissolved organic compounds which enter Chile’s rivers from salmon farms, and have published a report in the journal Scientific Reports, warning that these substances are placing huge strain on ecosystems and are changing entire biological communities.