The Modoc sucker (Catostomus microps) is a rare species of freshwater fish native to northern California and southern Oregon.

[8] Specifically, non-breeding body coloration of both sexes’ ranges from greenish brown to light blue to dark gray and olive.

[7] They have lighter coloration on the sides of the body with generalized mottling, usually with 3–4 darker spots similar in size to those of Sacramento suckers.

[3] The current habitat range of the Modoc sucker is quite extensive, covering approximately 68.4 kilometers (42.5 miles) of water.

[7] These streams are usually surrounded by vegetation and shade canopy like junipers, aspens, conifers, cottonwoods, willows, and chokecherries.

[13] For example, Ash Creek within the Grand Canyon are bordered by dense willow forests, which are closely surrounded by native grasslands or farmland.

[6] Secondly, the water quality needs to be not only moderately clear but preferably partially shaded by trees, shrubs, or boulders for better prevent from large predators.

[9] It is important to note that Modoc suckers are rarely seen in headwater streams with steep gradients and swift currents.

The stream habitat has substrates of sediment and cobble with large amounts of detritus in the water that the fish uses for cover.

Specific physiological conditions need to be met for the Modoc sucker to reach sexual maturity and be capable of reproduction.

In detail, they prefer to spawn on the bottom of fine to medium gravel ponds at water temperatures of 13.3 to 16.1 degrees Celsius from midday to mid-afternoon, approximately 10:00 a.m. to 4:00 pm.

[8] The average lifespan of Modoc suckers is generally 3 to 4 years accompanied by a body length that rarely exceeds 160 mm.

[5] The age and growth of Modoc suckers are typically assessed using three main methods: otoliths, scales, and body length.

[7] The Modoc sucker has a diverse diet, with organic detritus, benthic invertebrates and algae as its main food sources.

While the juvenile stage feeds primarily on organic detritus and algae,[6] adults expand their diet to include the intake of chironomid larvae and other aquatic insects.

[8] This fish typically chooses to feed at the edges of slow-moving streams or at the bottom of ponds rich in detrital sediments and chironomid larvae.

[6] However, the study showed that Goose Lake rarely overflows and has in fact been largely isolated from the Pit River since the Pleistocene.

[6] However, studies as late as 2011 still found two species coexisting in Ash Valley and central Turner Creek, suggesting that these are potential contact and hybridization areas.

[13] A variety of factors contributed to the dramatic decline in its population, including geographic isolation, habitat degradation, channelization of streams, over diversion, predation by brown trout (Salmo trutta), and hybridization with the Sacramento sucker (Catostomus occidentalis).

However, after nearly three decades of relentless conservation efforts, the Modoc sucker, which is about 7 inches in length and lives up to five years, has emerged from the brink of extinction.

[10] A series of effective conservation measures taken by government departments, such as the construction of fences in riparian zones to prevent cattle grazing,[6] have contributed significantly to the recovery of the Modoc sucker population.

The population size of this species has remained stable, showing a strong ability to adapt to the environment, indicating that its survival has stabilized.

In 1973, channelization projects were initiated in some areas under the direction of the Soil Conservation Service to control flooding and streambank erosion.

[6] Such projects transformed streams that had been meandering with alternating pools and rapids into straight channels with continuous flow and high banks.

[6] Future channelization project of this magnitude should be weighed against the long-term ecological degradation it may cause, especially the potential impacts to native fish.

[15] The impacts of climate change are expected to be multifaceted, potentially leading to substantial habitat loss for the Modoc sucker.

[5] These invasive species are often better equipped to handle changing environmental conditions, potentially outcompeting the Modoc sucker for resources and territory.

There is also no direct evidence of people using the Modoc sucker for fishing activities as it was previously listed as endangered by the IUCN.