It feeds on algae, diatoms and detritus on the floor of shallow streams with sand, gravel or cobble bottoms.

It is found in only a few streams in southern California, and many of these in the Greater Los Angeles metropolitan area have been restricted to concrete channels.

Because of its small area of occupancy and vulnerability, the International Union for Conservation of Nature has rated this fish as "endangered".

The rivers they swim in are at cool temperatures (average of less than 22 °C or 72 °F), with variable flow as the suckers are well adapted to survive in the most intense flood conditions.

[6] Although some stretches of the rivers are 'wild' and protected by being within the Angeles National Forest area of the San Gabriel Mountains, the coincidence of this fish's range and the Greater Los Angeles metropolitan area, and flowing in concrete lined flood control channels, means that it is a species vulnerable to extinction.

The International Union for Conservation of Nature has rated this fish as an "endangered species" because of its decreasing area of occupancy and declining population.

Fish and Wildlife Service issued an expanded critical habitat determination for the Santa Ana sucker, which came into effect on January 13, 2011.