Below are the native and non-native fish found in Yosemite National Park.

Native fish

Six native fish species occur in the Merced River in Yosemite National Park, from Yosemite Valley to El Portal. Of these, only rainbow trout and Sacramento sucker occur as high in elevation as Yosemite Valley. Waterfalls created by Pleistocene glaciation blocked fish from populating the Merced River above Yosemite Valley and the Tuolumne River inside the park boundary.

Rainbow trout (Oncorhynchus mykiss)
California roach (Lavinia symmetricus symmetricus)
Sacramento pikeminnow (Ptychocheilus grandis)
Hardhead (Mylopharodon conocephalus) —California Species of Concern
Sacramento sucker (Catostomus occidentalis)
Riffle sculpin (Cottus gulosus)

U.S. Fish and Wildlife Service

Brown trout is one of Yosemite's six non-native trout species.

Non-native fish

Nine non-native species and one hybrid of non-native fish occur in Yosemite National Park. From the first recorded planting in 1877 until 1990, more than 33 million fish were stocked into waters of Yosemite, primarily trout in high elevation lakes and streams. Rainbow trout, although native to lower elevations, are non-native to waters higher in elevation than Yosemite Valley.  Arctic grayling, Dolly Varden and Piute cutthroat trout are believed to be extirpated, no longer existing, in the park.

Smallmouth bass (Micropterus dolomieu)
Arctic grayling (Thymallus arcticus)
Brook trout (Salvelinus fontinalis)
Dolly Varden (Salvelinus malma)
Brown trout (Salmo trutta)
Lahontan cutthroat trout (Oncorhynchus clarki henshawi)—Federally threatened
Piute cutthroat trout (Oncorhynchus clarki seleniris)—Federally threatened
Golden trout (Oncorhynchus mykiss aguabonita)
Rainbow trout (Oncorhynchus mykiss)
Rainbow-golden hybrid trout(O. mykiss aguabonita X  O. mykiss)