It does not inhabit the mainland. Not because it cannot survive there. Because it evolved in isolation on the Chatham Islands, separated from New Zealand by eight hundred kilometres of ocean. The Chatham mudfish exists only on these remote islands, a product of geographic isolation and evolutionary divergence. Kōwaro. The Māori name applies to mudfish generally. The Moriori people of the Chatham Islands likely encountered this species in island wetlands before European contact. However its restricted distribution and small size meant it was probably less significant as a food source compared to more abundant species. Today the Chatham mudfish serves as an indicator of wetland health on the islands. The Chatham mudfish reaches about 130 millimetres in length. Its body is cylindrical and elongated, coloured brownish-grey with irregular darker markings. It lacks pelvic fins like other mudfish species. The streamlined shape allows navigation through dense aquatic vegetation in island wetlands. Unlike some mainland relatives, it cannot survive prolonged drought, requiring permanent water sources. Spawning occurs in spring and summer. Eggs are laid amongst submerged vegetation in shallow water. The larvae hatch and remain in freshwater completing their entire life cycle without marine migration. Diet consists of aquatic insects and small crustaceans. The fish feeds on drifting prey caught in current or picked from vegetation surfaces in shaded wetland sections. Threats come from multiple directions. Habitat modification from agricultural development destroys wetland areas. Introduced predators such as trout and perch compete for resources and prey on juveniles. Drainage for farming removes essential water sources. Climate change may alter rainfall patterns affecting water availability. Each threat compounds the others. The Chatham mudfish has nowhere else to go. It is endemic to these islands. If it disappears here, it disappears everywhere. Classified as Nationally Critical, the Chatham mudfish faces an extremely uncertain future. Its distribution is extremely limited, confined to specific wetland systems on the Chatham Islands. Each remaining population represents a genetic reservoir vital for species survival. Conservation efforts focus on protecting remaining wetlands from drainage and development. Controlling introduced predators offers some hope. But the islands face ongoing pressure from agricultural expansion. The land is valuable for farming. The mudfish requires only intact wetland habitat. Reconciling these competing needs on remote islands determines whether this unique endemic species survives extinction.