As juveniles pikeminnows feed off of insects, insect larvae, and zooplankton, which are very small organisms like the brine shrimp commonly sold at pet stores as fish food. Once a juvenile pikeminnow has grown to about four inches in length its’ predatory instincts start to kick in and its’ diet alters towards other fish.
As adults they enjoy the fast, rapid waters that are present in the Green River waters of Wyoming, but migrate to backwater areas with little to no current to breed. The babies grow in the slow moving waters until they are about eight inches in length and their living preferences change to enjoying deeper waters and rapid currents. Pikeminnows seem to not care a lot when it comes to the temperature of the waters they live in. They live in waters of varying temperatures, ranging from a frigid fifty degrees Fahrenheit to a sweltering ninety-five degrees Fahrenheit. Whereas most other fish species are differentiated between cold and tropical waters, but even tropical fish don’t like the water to be higher than eighty-two degrees Fahrenheit.