The Santa Ana sucker (Catostomus santaanae) is a freshwater ray-finned fish, endemic to California. It is closely related to the mountain sucker and has dark grey upper parts and silvery underparts. It grows to a maximum length of , but most adults are much smaller than this. 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". Description The Santa Ana sucker is closely related to the mountain sucker, and quite similar in appearance. Color is dark grey above and silvery-white below; the sides have a faint pattern of darker blotches and stripes. There are distinct notches where the upper and lower lips meet, and the lower lip is narrower in the middle, with only 3 or 4 rows of papillae at that point. The dorsal fins have 9 to 11 rays, while the pelvic fins have 8 to 10 rays. These suckers do have an anatomy variation by sex where females have tubercles on caudal peduncle and anal fin while men have an additional tubercles on lower half of caudal peduncle, anal, and caudal fins. The caudal peduncle is somewhat longish. In contrast to the mountain sucker, the membrane between the rays of the tail fin is pigmented. Length has been recorded up to , but less than is more typical. Also like the mountain sucker, it feeds on diatoms, other kinds of algae, and detritus, which it obtains by scraping surfaces such as rocks. It also eats the occasional insect larva, with larger fish observed to consume insects more frequently. The breading habits of Santa Ana Suckers do not differ from other species of suckers as the female fish are attended by at least 2 male fishes during mating seasons. A female sucker can release between 4,000 and 16,000 eggs amongst her gradual breeding process. Their living patterns consist of being a nonmigrant species that are short-lived with around 4 years of time, on average. Habitat Santa Ana Suckers live in small to medium size streams throughout the year in Southern California. They notably thrive in freshwater conditions. The