Abstract
In 2023, the gold / Asian clam ( Corbicula fluminea ) was first recorded in Aotearoa New Zealand (Aotearoa‐NZ). This non‐native species (NNS) could impact Aotearoa‐NZ freshwater ecosystems more than any previous invader. It could alter food webs, physical habitats and water clarity, disrupt nutrient cycling and restructure plankton / macroinvertebrate / fish assemblages. I have reviewed clam impacts on trophic ecology, water chemistry and fish habitat from international studies, focusing on native and non‐native fish species also present in Aotearoa‐NZ and on ecological analogues. I identified fish that could be negatively affected and those which could benefit. Small benthic ‘riffle‐run specialists’ could be vulnerable to some extent, facing both habitat modification and competition for shared food resources. Fish frequenting backwaters or slower‐flowing reaches could be even more vulnerable, as clam densities are often highest here. Native galaxiids, already threatened by habitat fragmentation/degradation, may be at further risk from additional pressures of a clam invasion. Among introduced fish, salmonids may lose spawning habitats, whereas generalist ‘pests’ such as catfish and koi may benefit from clam‐derived food resources. C. fluminea may represent a significant new stressor for Aotearoa‐NZ freshwater ecosystems. The hyptheses generated in this article are important to help anticipate species‐specific responses, which will be essential for strategies to protect native fish.