Freshwater fish should be added to the list of species that are threatened by emerging fungal diseases (M.C. Fisher et al. Nature 484, 186–194; 2012). Government agencies need to adapt their fish-monitoring programmes to establish the extent of the damage these pathogens are causing.

Freshwater fish are important for millions of people in eastern Asia, for example, but fungal diseases are spreading fast there, helped by invasive species that carry fungal pathogens (R.E. Gozlan et al. Fish Fish. 11, 315–340; 2010).

It is essential to convince cash-strapped government agencies that experimental work can give insight into real-world epidemiology, and that a major impact of disease on fish populations could go unnoticed using current monitoring systems, which don't work for fish living in muddy waters.