A long, narrow, muscular and rope-like fish, often appearing dark brown or black. There is a continuous fin running along the top of the body to the tip of the tail (the dorsal and anal fins merge forming a continuous ridge along the top of the eel’s body). They are slippery and slimy to the touch – this mucus enables the eel to survive out of water for extended periods. At different life stages eels do appear very different changing from thin transparent ‘glass eels’ found at sea, to 50mm long young ‘elvers’ which grow to sexually mature ‘silver eels’ which may be up to a metre long.