Siksika ottae is an extinct prehistoric cartilaginous fish, lived during the Upper Mississippian. It has been discovered at the well known Bear Gulch Formation (Montana, United States), dated at Carboniferous period. It is known mostly on the base of fossil teeth, but also partially neurocranium and mandibles which hint a close relationship to coeval petalodontiform sharks Janasssa and Netsepoye. Dentition is generally heterodont. Siksika means literally Blackfoot, being named after the Siksika Nation.