Longfin eels can be found throughout New Zealand. They live mainly in rivers and inland lakes but can be found in almost all types of waters, usually well inland from the coast.
They are legendary climbers and have made their way well inland in most river systems, even those with natural barriers. Elvers (young eels) swimming up river will climb waterfalls and even dams by leaving the water and wriggling over damp areas. It is not unheard of for an eel to climb a waterfall of up to 20 metres.
When eels begin life, they are a tiny one millimetre in length. During their life, they can grow up to two metres long.
Compared with many other fish, eels are slow growing – a longfin may grow only between 15-25mm a year. They can also live for many years. Large longfins have been estimated to be at least 60 years old.
The biggest eels are usually old females that have been slow to reach sexual maturity and, for reasons that are not yet understood, have not migrated to sea to breed.