My dad grew up obsessed with small waterways. As a child he scoured streams, ponds and, perhaps inevitably for someone living on the edge of Manchester, canals. Soon he had tanks filled with dozens of small creatures in his bedroom. This included wildlife that was plentiful in the 1950s but that I’ve never seen: shellfish such as freshwater limpets, invertebrates such as the charismatic water scorpion.
Horse leeches would escape and wander the house at night, while his swan mussels required large tanks of mud instead of water. Family connections took him to the Macclesfield canal at Higher Poynton and the Lancaster canal, with its huge Lake District views. Neither had boat traffic at that time, so were undisturbed and crystal clear, with their fish and crustaceans visible.
Like so many ecological settings, freshwater habitats were damaged in the late 20th centu