Euteleostei

Protacanthopterygii is a superorder of ray-finned fish. They inhabit both marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roughly 150 million years ago; fossils of them and the closely related Otocephala are known from throughout the Cretaceous.

thumb|Salamanderfish observed in habitat, 2023 Lepidogalaxias salamandroides is a species of small freshwater fish of Western Australia. It is the only member of the family Lepidogalaxiidae and genus Lepidogalaxias. Common names for this fish include salamanderfish and Shannon mudminnow. Although it is not a lungfish, it resembles lungfish in several respects, including its ability to survive dry seasons by burrowing into the sand. It is on the IUCN Red List as Endangered.

thumb|left|Stomiidae ([[Stomiiformes), from top to bottom:Northern Stoplight Loosejaw (Malacosteus niger),Eustomias braueri,Bathophilus vaillanti,Leptostomias gladiator,Rhadinesthes decimus,Photostomias guernei and its mouth]]

The Neoteleostei is a large clade of bony fish mostly consisting of marine clades. Only three lineages have freshwater species: Percopsiformes (Troutperches), which lives exclusively in freshwater, Gadiformes (cods), which is largely marine except from burbot that live in freshwater and a few populations of cod in brackish water, and the Percomorpha, which, in addition to several marine groups, also have many freshwater forms.

Euteleostei, whose members are known as euteleosts, is a clade of bony fishes within Teleostei that evolved some 240 million years ago, although the oldest known fossil remains are only from the Early Cretaceous. It is divided into Protacanthopterygii (including the salmon and dragonfish) and Neoteleostei (including the lanternfish, lizardfish, oarfish, and Acanthopterygii).