Ive never seen a Sacramento blackfish out of the water; I see them all the time in Clear Lake when Im sightfishing. What a cool fish. Heres a description of the species range from Moyle 2002 (awesome book if you are into the fish of California):

"Native to low-elevation reaches of the Sacramento and San Joaquin Rivers and their major tributaries, as well as to Clear Lake and the Pajaro and Salinas Rivers. They are prsent in the Russian River and in a few central California reservoirs (e.g. Shasta, Hennessy, Lagoon Valley). In the San Francisico Bay region they are present in the Delta and in Coyote, Alameda, and Walnut Creeks. They have been transported by the California Aqueduct to San Luis Reservoir, where they are common, and they can be expected in any reservoir in southern California that contains water from the aqueduct."