HomeFish encyclopediaRay-finned fishesPerch-like fishDuckbillsOpalfish Opalfish (Hemerocoetes monopterygius) Scientific name: Hemerocoetes monopterygius Schneider, 1801 The Opalfish (Hemerocoetes monopterygius) is a marine fish of the family Percophidae. Native range: Southwest Pacific, New Zealand. Species factsScientific nameHemerocoetes monopterygiusFamilyPercophidae (Duckbills)OrderPerciformes (Perch-like fish)ClassActinopterygii (Ray-finned fishes)EnvironmentMarine; demersalClimateSubtropicalDistributionSouthwest Pacific: New Zealand.Conservation status (IUCN)Least Concern (LC)Threat to humansHarmlessResilienceMedium, minimum population doubling time 1.4 - 4.4 years (tmax=3; k=0.26-0.31) SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0.Last updated 27 September 2026