Cave loaches have been found in Germany.
Increased numbers of sea lice in farmed salmon could affect wild fish too.
A successful restoration project on the Swindale Beck River provides an ideal habitat for breeding fish.
Study suggests adapting to life on land wasn't the biggest challenge facing fish coming ashore millions of years ago.
As Finding Dory hits UK cinemas this week, science writer Stuart Blackman reveals whether fish really do have companions.
Discover more about the fascinating array of fish species in British waters and vote for your favourite.
Aside from mosquitoes, which creatures feed on blood?
10 tips on how to photograph freshwater fish with photographer Jack Perks.