Echyridella menziesii, the New Zealand freshwater mussel, also known by its Māori names kākahi, kāeo, and torewai, is a species of freshwater mussel endemic to New Zealand.
They were an important food source for the Māori, but like many freshwater mussels worldwide, are now endangered by pollution and eutrophication of rivers, and the introduction of new species of fish leading to actions via the Treaty of Waitangi claims process.
Formerly common in lakes, rivers and streams in New Zealand.
Its reproductive cycle is typical of other freshwater mussels, requiring a host fish on which its larvae (glochidia) parasitise and metamorphose into juvenile mussels – most commonly the kōaro (Galaxias brevipinnis).
The destruction or modification of the habitat of the New Zealand freshwater mussel is likely to be a factor in the decline of its population. This modification or destruction of freshwater habitat is also likely to be a factor in the decline in numbers of the mussel’s host fish, the kōaro.
In May 2014 the Department of Conservation classified the New Zealand freshwater mussel under the New Zealand Threat Classification System as “At risk” and “declining”.