Due to the rugged terrains and general inaccessibility to the mountainous parts of New Britain via proper road systems, the inland rivers and streams remain unprospected of its ichthyofauna. By using underwater visual census, we documented freshwater fish covering 16 rivers and creeks. A total of 22 species were recorded of which most were gobies (Gobiidae) and freshwater eels (Anguillidae). We documented the lobed river mullet (Cestraeus plicatilis), Kolobangara goby (Lentipes kolobangara) and the Ségura gudgeon (Belobranchus segura) for the first time in Papua New Guinea outside of their known ranges. Our record on spine-finned fishes (Kuhlia spp. and Mesopristes cancellatus) far inland (c.a. 40 km from the coastline and at >600 m a.s.l) further increased our knowledge on how far these fishes are able to traverse inland given that there are no natural barriers such as waterfall. We provide an account of each species recorded and recommended for no introduction of exotic fish in the freshwaters of New Britain, Papua New Guinea.