Chub subpopulations inhabiting Albanian river systems outside the Drin (sq. Drini; mk. Дрим) River catchment, including the Vjosa (el. Αώος/Aoös) River which extends into northwestern Greece, are treated as conspecific with Squalius platyceps for the purposes of this assessment (Geiger et al. 2014, Shumka et al. 2018, 2023). However, their taxonomic status requires further investigation (Barbieri et al. 2015, Shumka et al. 2018).

According to molecular data, this species is also closely-related to the congener Squalius prespensis (Geiger et al. 2014, Tsoupas et al. 2022).

Global and European regional assessment: Least Concern (LC)
EU 27 regional assessment: Vulnerable (VU°)

Although this species' population trend may be decreasing due to habitat degradation, there is no evidence that the rate of decline approaches the minimum threshold for Vulnerable under Criterion A (≥ 30% over the longer of 10 years or three generations). It does not approach the range thresholds for Vulnerable under Criterion B1 (extent of occurrence (EOO) < 20,000 km²) or D2, and Criterion B2 is precluded by its uncertain area of occupancy (AOO). The population size is understood to exceed 10,000 mature individuals, and does not meet the thresholds for Criteria C or D. There exists no quantitative analysis which would permit application of Criterion E.

Therefore, the Skadar Chub does not currently meet the thresholds for any Red List criteria, and it is assessed as Least Concern at the global and European regional scales.

In the EU 27 member states, the EOO is c. 3,759 km² and meets the threshold for the Endangered category under Criterion B1 (EOO < 5,000 km²). It is present at two to three locations where the quality of habitat is estimated to be declining. However, one of the two identified subpopulations comprises part of a larger transboundary subpopulation, hence its assessment is downlisted by one category from Endangered to Vulnerable under Criterion B (B1ab(iii)).

This species is endemic to the Western Balkans region, where its putative range extends from the Bojana (sq. Bunë) River in Montenegro and northern Albania to the Vjosa River in southern Albania and Greece, including the Skadar (sq. Liqeni i Shkodrës; cnr. Skadarsko jezero) and Ohrid (sq. Liqeni i Ohrit; mk. Охридско Езеро) lake basins (see 'Taxonomic Notes').

In Montenegro, it has been introduced to Nikšić Polje, which is drained by the upper Zeta River (Lake Skadar catchment) but is only connected to the remainder of the system by subsurface karstic conduits, the Piva accumulation lake in the upper Drina River (Danube River system), and a number of smaller artificial lakes and ponds.

Its extent of occurrence is 53,235 km², and in the EU 27 region it is 3,759 km².

This species' population size is unknown, but is understood to exceed 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.

There exist a series of plausible threats, but recent (post-2016) field observations indicate that it is among the most abundant native fishes at some locations, e.g., Lake Skadar and the lower Zeta River (Montenegro), lower Vjosa River (Albania), White Drin River (Republic of Kosovo).

In the EU 27 member states, two extant subpopulations have been identified in the Vjosa River system, where they are separated by the Aoös Springs Dam. One subpopulation is isolated in an artificial accumulation lake above the dam, whereas the other is part of a much larger subpopulation which includes downstream reaches of the river in Albania.

This species is present in rivers and streams at various altitudes, but tends to exhibit a preference for pools, glides and floodplain wetlands with slow to moderate flow. It also occurs in the naturally oligotrophic lakes Skadar and Ohrid, and has colonised some artificial accumulation lakes.

It is largely a benthic predator feeding on aquatic invertebrates, but also consumes organic detritus, plant material and smaller fishes.

Adult individuals reach sexual maturity at age 3+ or 4+. This species is a fractional, polygamous spawner and the annual reproductive period extends from late March to June. The eggs are deposited among coarse stony substrata or tangles of woody roots.

In Lake Skadar, it reportedly hybridises with the sympatric Skadar Bleak (Alburnus scoranza).

This species is plausibly threatened by river regulation and other forms of anthropogenic habitat degradation. In particular, the ongoing construction of large dams plus smaller weirs and other barriers has severely altered natural flow and sedimentation regimes, blocked migration routes, fragmented subpopulations, and reduced the extent of suitable habitat for all life stages. Hydroelectric schemes have created unnatural fluctuations in discharge and water temperature (hydropeaking and thermopeaking) which bring about artificial dewatering of downstream river stretches and loss of stable nursery habitat for juveniles. Furthermore, the combined effect of hydropeaking, dam flushing operations, changes in land use, and the removal of riparian vegetation has increased accumulation of fine sediments at some spawning sites, plausibly impairing the hatching and survival rates of eggs and larvae.

The quality of available habitat has been further diminished by bank stabilisation, channelisation and other efforts to enhance flood protection or exploit water resources for irrigated agriculture. Some habitats may also have been damaged by the industrial extraction of riverine gravel or other sediments for urban development.

This species is also 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, siltation or discharge of toxic substances. Pollution can be particularly impactful when discharge is reduced during the summer.

For example, native fish declines in Lake Skadar have been ongoing since the mid-20^th century. The lower reaches of the affluent Morača River system are polluted due to long-term discharge of agricultural and industrial contaminants plus municipal wastewater from the city of Podgorica and other communities. As a result, the naturally oligotrophic lake has become increasingly eutrophic, leading to structural changes in the resident planktonic and zoobenthic communities plus the wider food chain. A number of non-native fish species have been introduced to the basin, including Goldfish (Carassius auratus), Common Carp (Cyprinus domestic strain), Eurasian Perch (Perca fluviatilis), Eurasian Pikeperch (Sander lucioperca), Pumpkinseed (Lepomis gibbosus), Topmouth Gudgeon (Pseudorasbora parva), Brown Bullhead (Ameiurus nebulosus) and Rainbow Trout (Oncorhynchus mykiss). All of these taxa can exert detrimental pressures on native freshwater fauna through increased competition, predation, habitat degradation, or transmission of pathogens, and most are present elsewhere in the Skadar Chub's range where their establishment is favoured by dam construction.

In Lake Ohrid, excessive water abstraction and eutrophication in neighbouring Lake Prespa (sq. Liqeni i Prespës; mk. Преспанско Езеро; el. λίμνη Πρέσπα), with which it shares a subterranean hydraulic karstic connection, is believed to be partially responsible for increasing nutrient levels. Furthermore, the nearby Sateska River was in 1962 diverted from its former confluence with the Black Drin (sq. Drini i Zi; mk. Црн Дрим) River into Lake Ohrid in order to improve the water balance of the lake and enhance its potential for hydropower generation. However, the Sateska has since become a major source of biochemical oxygen demand and sediments transported into the lake.

In the EU 27 member states the majority of this species' range comprises an artificial lake plus a stretch of the upper Vjosa River which flows through an extensively-cultivated upland plateau, where it receives diffuse and point-source pollution from surrounding agriculture and a nearby town, respectively.

This species is a secondary component of the commercial fisheries which operate on lakes Skadar and Ohrid.

Closed fishing seasons and minimum catch size limits are established in lakes Skadar and Ohrid (Skadar closed season in the Republic of North Macedonia only, Ohrid catch size limit in Albania only).

No other conservation management is in place exists, but this species is present within the boundaries of various protected areas.

In particular, the Montenegrin part of Lake Skadar was declared a National Park in 1983 and designated a Ramsar Wetland of International Importance (site no. 784) in 1995, while the Albanian portion was nationally-protected and added to the Ramsar Convention in 2006 (site no. 1598). The lower Zeta River in Montenegro has been a protected area since 2019.

The North Macedonian portion of Lake Ohrid has been included in UNESCO's list of World Heritage sites since 1979, while a bilateral agreement between Albania and North Macedonia resulted in establishment of the Ohrid Watershed Management Committee in 2004 and the Ohrid-Prespa Transboundary Biosphere Reserve in 2014. At the national scale a number of additional protected sites have been created around the lake, including the Pogradec Aquatic and Terrestrial Protected Landscape and Drilon National Monument in Albania, and the Lake Ohrid Monument of Nature and Galicica National Park in North Macedonia. In April 2021 Lake Ohrid was added to the Ramsar List of Wetlands of International Importance (site no. 2449). A number of sections of the Drin River and its tributaries flow through protected areas of various designations and proportions.

In 2023, the entire Vjosa River catchment was designated as Europe's first Wild River National Park. Several sites in the upper Vjosa, Greece, are included in the European Union's Natura 2000 network and comprise the majority of this species' range in the EU 27 member states.

A deeper understanding of this species' present distribution, population status (size and trend), life history and response to the ongoing threats would likely prove beneficial in the design of any structured management plan.