In Europe this taxon is frequently referred to as Eupallasella percnurus following Howes (1985), because no range-wide taxonomic review has yet been published (Kusznierz et al. 2017).

Subpopulations inhabiting the Volga River system are morphologically divergent from those present elsewhere, and may comprise a distinct species (Kusznierz et al. 2011, 2017).

The Lake Minnow has an extensive native distribution, and does not approach the range thresholds for Vulnerable under Criterion B (extent of occurrence (EOO) < 20,000 km², area of occupancy (AOO) < 2,000 km²) or D2. Although the population trend appears to be decreasing, the rate of decline is not understood to approach the threshold for Vulnerable under Criterion A (≥ 30% over the past ten years or three generations). The population size far exceeds 10,000 individuals; therefore, it does not approach the thresholds for Criteria C or D. There exists no quantitative analysis which would permit application of Criterion E.

Therefore, this species does not currently approach the thresholds for any Red List criteria, and it is assessed as Least Concern.

This species has an extremely wide distribution covering the majority of northern Eurasia, where the bulk of its range comprises river systems draining to the Arctic Ocean from the Russian Federation, Kazakhstan, northwestern China and Mongolia, extending eastward from the Northern Dvina River to the Anadyr River.

In the European region, it is present in the Neman, Oder (pl. Odra), Vistula, Dnieper and Volga river systems in the Baltic, Black, Azov and Caspian Sea basins. It is absent from the lower Volga catchment, and in the Don River watershed has been recorded only at Lake Borove in the upper Seversky Donets River.

In the Western Pacific basin, it is present in rivers draining to northern and western parts of the Sea of Okhotsk and Sea of Japan, from the Penzhina and Talovska river systems in northern Kamchatka, Russian Federation, to the Sŏngch'ŏn River, Democratic People's Republic of Korea. It is also found on the islands of Sakhalin, Russian Federation, and Hokkaido, Japan, while the southern limit of its Pacific range is the Yalu River, which drains to the Yellow Sea at the border between Democratic People's Republic of Korea and the People's Republic of China.

The range map accompanying this assessment appears patchy in Poland, since it is the only country in which this species' extant distribution is comprehensively understood. The precise limits of its range in other territories is somewhat unclear.

This species' population size is unknown, but significantly exceeds the minimum threshold for Red List criteria (< 10,000 mature individuals). The current population trend has not been quantified, and the number of subpopulations is unclear.

The area of occupancy is inferred to be declining in Poland, Lithuania and Ukraine, where numerous subpopulations have been extirpated since the mid-20^th century. In Poland, the number of locations had fallen from around 160 in 2009 to 90-100 by 2023, while in Lithuania only three of 12 known subpopulations remain (see 'Threats').

The situation elsewhere is unclear. While it is plausible that declines have occurred in areas exploited for agriculture, industry or urban growth, a significant proportion of its range in the Russian Federation remains relatively unimpacted by human development.

This gregarious species inhabits lentic, often dystrophic, lowland environments including freshwater lakes, spring-fed karstic wetlands, swamps, gyttja bogs, peatlands, floodplain marshes and oxbows. It is occasionally encountered in shallow, slow-moving tributary rivers and streams. Many of its habitats are characterised by seasonal fluctuations in surface area, with individuals able to disperse short distances during spring flood events. It is able to tolerate a wide range of pH (at least 5.1-9.5), water temperature and dissolved oxygen parameters, and often spends several months of the year beneath surface ice. Individual subpopulations can occupy very small waterbodies, and may be reduced to tens of individuals during periods of drought or high summer temperatures.

It frequently colonises artificial environments such as flooded quarries or water retention ponds. For example, in eastern Poland it primarily occupies small (surface area < 0.001 km²), shallow (1-2 metres deep) pools formed by inundated diggings at former peat or clay extraction sites, which are no more than 100 years old. Most of these are isolated and shrinking over time (see 'Threats'), whereas others are connected to nearby waterbodies during floods. Many of them are susceptible to temporal desiccation which can lead to significant fluctuations in abundance, including extirpation events.

This species is a generalist omnivore which feeds opportunistically on a wide range of small items, including benthic and planktonic invertebrates, plant material and the early life stages of amphibians and other fishes.

The maximum recorded lifespan is 6 years, and sexual maturity is reached at age 1-2+. The annual reproductive period extends from late spring to summer, with the precise timing somewhat dependant on latitude and triggered by water temperatures of 7-15°C. This species is a fractional, polygamous spawner and the eggs are typically deposited among aquatic vegetation where they hatch after 10-15 days. Under warmer conditions, the incubation time can be as little as 5 days, while at temperatures above 28°C the ability of males to produce viable milt is considerably reduced (see 'Threats').

This species is threatened by ongoing anthropogenic habitat degradation, particularly drainage of swamps and wetlands in order to reclaim land for agricultural or urban development. Extensive tracts of floodplain habitat have also been lost due to the installation of canal systems, dams and other river regulation measures, which have altered natural flow regimes and interfered with groundwater levels. In some areas, flood cycles have been negatively impacted by mining or other industrial activities. These processes have significantly reduced the extent and quality of habitat for all life stages, in addition to fragmenting subpopulations by limiting dispersal between different locations.

This species is further threatened by diffuse and point source agricultural, domestic and industrial pollution, which has reduced the extent and quality of habitat at some locations due to eutrophication or discharge of toxic substances.

In some parts of its range, small waterbodies have been artificially deepened or expanded in order to utilise them for recreational fisheries or water retention. Such modifications are typically followed by the introduction of other fish species which may reduce Lake Minnow abundance through increased competition, predation or habitat degradation, especially at locations where it is the only resident fish species. These include both native and non-native taxa such as Goldfish (Carassius auratus), Prussian Carp (Carassius gibelio), Common Carp (Cyprinus domestic strain), Eurasian Perch (Perca fluviatilis) and Northern Pike (Esox lucius). At many locations in the western part of its range it is threatened by introduction of the non-native Chinese Sleeper (Perccottus glenii) and/or Topmouth Gudgeon (Pseudorasbora parva), both of which predate on different life stages, negatively affect the foraging behaviour of native fishes through aggressive interactions, and can exert profound effects on macroinvertebrate community structure. Topmouth Gudgeon is also a vector for the parasite Sphaerothecum destruens, which may represent an additional threat. In eastern Poland, the predatory Brown Bullhead (Ameiurus nebulosus) has been widely-introduced and is understood to have caused extirpation of the Lake Minnow at several locations.

An increasing prevalence of prolonged droughts driven by climate change might cause some shallow wetlands to dry out completely during the summer, and recolonisation may not be possible at isolated locations. Moreover, reproductive functioning is impaired when water temperatures become too high during the summer.

In Poland, the small artificial ponds which comprise this species' primary habitat are often drained or filled in as a result of both natural and anthropogenic processes such as water abstraction, a lack of natural recharge, accumulation of organic sediments or overgrowth of emergent vegetation. Fly tipping is also common, and can quickly lead to pollution in these restricted environments.

There exists evidence that increasing rates of acidification at some peatland locations, the drivers of which are currently unclear, may hamper the development of early life stages.

This species is harvested commercially in some eastern parts of its range, e.g., parts of the Lena and Omoloy river systems, Russian Federation, but few details are available.

It is sometimes used as live bait by recreational anglers targeting piscivorous species.

This species is included (originally as Phoxinus percnurus) in Annexes II and IV of the European Union Habitats Directive.

It is nationally-protected and listed in the respective Red Data Books of Lithuania, Poland and Ukraine.

It is present within the boundaries of numerous protected areas, including several national parks. In the EU 27 member states, a number of these are included in the Natura 2000 network.

A series of direct conservation actions have been implemented in Poland, where an ex situ breeding programme has been underway since 2002. Captive-bred juvenile individuals were released at several previously unoccupied sites in the vicinity of Warsaw between 2004 and 2010, and self-sustaining subpopulation now exist at 3-4 of these. In 2016, several hundred wild individuals from a large subpopulation in Lublin Voivodeship were translocated to three sites in the nearby Polesie National Park. Habitat improvement measures carried out at some Natura 2000 sites have included the removal of accumulating sediments from artificial ponds and the removal of overgrown vegetation such as reedbeds.

A deeper understanding of this species' population trend and current distribution, particularly the identification of priority conservation sites, would likely prove useful in the development of future management schemes. Given the extent of its range, such efforts should ideally be coordinated at local or regional scales.

This species' taxonomy is reportedly in need of clarification, particularly in the eastern and western extremities of its range.