We love and care for your canals and rivers, because everyone deserves a place to escape.
It's that time of year when young people take their GCSEs. So we want to know if you too know your fish chemistry. But (spoiler alert) you'll need to tackle this one differently if we're to let you off the hook!
Why not try our biology quiz
If chemistry is not your formula for success, try our GCSE fish biology quiz
Last date edited: 21 April 2017