Limnomysis benedeni Czerniavsky, 1882

Common Name: Caspian slender shrimp

Synonyms and Other Names:

Caspian slender mysid, Danube mysid, Pontian mysid, Limnomysis behningi Zhadin and Gerd, 1961, Limnomysis brandti Czerniavsky, 1882, Limnomysis schmankeviczi Czerniavsky, 1882, Mysidella bulgarica Valkanov, 1936, Onychomysis mingrelica Czerniavsky, 1882


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Identification: his species is distinguished from other species of the family Mysidae by the following combination of morphological characters: cylindrical eyestalks are 1.4–2.3 times the length of the cornea. Antennal scale is setose all around, with a distinct, sexually dimorphic apical segment. Antennal tip is rounded with an indistinct or weak ventral flexure in females, whereas this feature is more acute and with stronger flexure in males. The anterior margin of the carapace extends into a pair of lateral spine-like processes. Pleopods are reduced to small setose plates in both sexes, except for the third and fourth pleopods in males. The third male pleopod is fused to a two-segmented plate; the fourth male pleopod has a small, distinct endopod. The exopod is much longer but basally fused with the two-segmented sympod and is terminally of unique shape (occasionally with bifid tip). The telson is short, stout, and sub triangular, with 14 spines along the lateral margins and a rounded apical incision armed with 4–10 laminar processes. Coloration is dark brown to translucent (Kelleher et al. 1999; Wittmann 2009). A detailed description of L. benedeni is available in Bacescu (1954).

Size: Body length of adults, measured from the tip of the rostrum to the end of the telson, is typically in the range of 6–13 mm.

Native Range: Coastal waters of Black and Caspian Seas and upstream in connecting rivers (Bacescu 1954).

Nonindigenous Occurrences: In 1946, L. benedeni was found in the Danube River near Budapest, Hungary (Dudich 1947). This was prior to it being intentionally introduced to several locations along the Baltic coast of the former Soviet Union, beginning with the Dnieper River, Ukraine in 1947 (Leppäkoski 1984). In 1950, it was stocked in Lake Balaton, Hungary to enhance fishery production (Woynarovich 1955). Stocks taken from the Dnieper River in 1690 were used to stock the Kaunas Reservoir in Lithuania, and L. benedeni subsequently spread along the River Neman down to the Curonian Lagoon on the Baltic coast (Olenin and Leppäkoski 1999; Arbaciauskas 2002). From 1973 to present, this species has undergone vast range expansion throughout Asian and European waterways. In 1975, this species appeared in Lake Aral (Kazakhstan and Uzbekistan), possibly due to inadvertent stocking in the late 1950s and 1960s (Aladin et al. 2003). It was first found in 1977 in the Tisa River, Serbia and has since spread to the Sava and Zapadna Morava River basins (Zoric et al. 2020). The upper Danube River in Germany was reached in 1993 (Wittmann 1995), and in 1998 this species was found in the Main-Danube Canal. By 1998, L. benedeni had reached French waters of the middle Rhine River and the Rhine delta (Ketelaars et al. 1999; Wittmann and Ariani 2000). In 2003, this species was found for the first time in Poland, in the River Odra (Michels 2005). Further expansion from the Rhine led it to reach Switzerland (Wittmann 2007) and Belgium by 2005. Lake Constance was reached in 2006, marking the common borders of Austria, Germany, and Switzerland (Fritz et al. 2006; Löffler 2010). In 2007, L. benedeni appeared in Belarus for the first time at three stations along the River Pripyat (Semenchenko et al. 2007), where it may have spread from introduced populations in the Dnieper River.

This species is not currently in the Great Lakes region but may be elsewhere in the US. See the point map for details.

Ecology: Limnomysis benedeni is found primarily in shallow (0.5–5 m), near-shore locations, though it has been reported in waters as deep as 33 m (Steinmann 2009). Kelleher et al. (1999) note high densities at depths of 0–0.5 m and a preference for still water. Wittmann (1995) reports a maximum current velocity tolerance of 0.5 m/s, though this species has occasionally been found at higher velocities (1.5 m/s); L. benedeni may tolerate such conditions by maintaining physical contact with the substrate (Wittmann 2007). Under bright conditions, this species prefers habitats with stands or spots of dense submerged vegetation, including macrophytes (especially stonewort), submerged tree roots, and flooded terrestrial weeds (Weish and Türkay 1975; Wittmann 1995; Wittmann et al. 1999; Gergs et al. 2008). Limnomysis benedeni shows great habitat plasticity and will select from a variety of other structured habitats—such as spaces between stones or boulders, stones overgrown by mussels, empty shells, branches of submerged trees, and coarse debris—when sufficient plant cover is unavailable. High densities of mysids have been observed in and on coats of filamentous algae covering concrete walls, and occasionally, individuals are even observed on the bare surface of soft sediment or concrete walls (Wittmann 2007). In shallow habitats, L. benedeni is usually solitary or found in loosely aggregated groups, tending to stay a few centimeters above the substrate or rest directly on it. In the turbid waters of coastal lakes or in deeper waters of clear continental lakes, this species may form dense aggregations of hundreds or thousands of individuals (Wittmann 2009). At night, its distribution becomes more scattered. Part of the population is found in surface waters while others remain at greater depths (i.e., it undergoes vertical diel migration) (Wittmann et al. 1999).

Salinity is a primary limiting factor to the distribution of L. benedeni. Most populations occur in freshwater; however, mass occurrences have been observed in coastal and continental lakes with salinities of 0.5–5 PSU (Wittmann 1995, 2007), and a few populations have been reported in habitats with 6–14 PSU (Bacescu 1954; Komarova 1991; Ovcarenko et al. 2006). Wittmann (2009) reports that it prefers a salinity range of 0.1–3 ppt while it is able to tolerate 0–14 ppt. In a laboratory study by Bacescu (1940), a low tolerance was exhibited for salinities above 10 PSU. In contrast, Ovcarenko et al. (2006) report that L. benedeni is largely unaffected by salinity increases up to 19 PSU and shows only about 25% mortality when exposed to 23 PSU for 24 hours. It is not until 24 hours of exposure to 34 PSU that a 100% mortality rate is observed.

This species favors slightly alkaline waters, as mass occurrences are found only in areas with pH >7.7 (Wittmann 2007). Preference for alkaline waters is also suggested by reduced juvenile oxygen consumption at pH 8.4 compared to pH 5.4 (Szalontai et al. 2003). Overall, it is able to tolerate a pH range of 5.5–9.6, with values of 7.3–8.6 comprising its optimal range (Wittmann 2009). The lower oxygen limit tolerated by L. benedeni in freshwater is 3.75 mg/L, which is relatively high among freshwater invertebrates though lower than lethal concentrations demonstrated for other freshwater mysids (Bacescu 1940; Wittmann 2007). Dissolved oxygen concentrations > 5.9 mg/L is reported as its optimal range by Wittmann (2009). Oxygen consumption rates for this species are 0.53 and 3.20 µg O2/mg dw/h at 0°C and 13°C, respectively (Szalontai et al. 2003). Limnomysis benedeni tolerates a wide range of temperature (0–31°C), while ideally inhabiting waters of 10–25°C (Wittmann 2009).

Limnomysis benedeni is primarily microphagous, with a diet consisting of phytoplankton, epilithon, detritus, and biofilms on macrophytes, while animal prey (chironomids, etc.) play a minor role (Dediu 1966; Wittmann and Ariani 2000; Gergs et al. 2008). Like other freshwater mysid species, L. benedeni plays an important role in the diets of fish (Bacescu 1940, 1954; Zhadin and Gerd 1961; Mordukhai-Boltovskoi 1979; Hanselmann et al. 2011; Specziár and Eros 2014).

As in all mysid species, L. benedeni shows strictly sexual reproduction. Eggs are fertilized upon or shortly after deposition in the brood pouch. A single female with fertilized eggs may be sufficient for establishing an entirely new population (Wittmann 2009). Breeding females are found from March/April to October/November (Bacescu 1954), with an overwintering generation reproducing in spring/summer, followed by one or two summer generations reproducing in summer to autumn (Wittmann 1984, 2009) for a maximum of 5 generations per year. The shortest generation time recorded was 6 weeks yielding 5 generations in a year in the Middle Danube River (Borza et al. 2014). Newly hatched individuals undergo two larval stages while within the brood pouch and molt to the fully mobile juvenile stage upon release. The number of eggs or larvae carried in the brood pouch increases with parent body size, with females typically carrying 12–40 eggs on average (range 2–46) (Wittmann and Ariani 2000; Gergs et al. 2008). Additionally, egg numbers and parent body size vary by season, with the spring generation carrying nearly three times the amount of eggs as the summer (Dediu 1965; Gergs et al. 2008). A single female is capable of producing several subsequent egg clutches  (Wittmann 2009).

Means of Introduction: Limnomysis benedeni has a moderate probability of introduction to the Great Lakes (Confidence level: High).

Potential pathway of introduction: Trans-oceanic shipping

Ricciardi and Rasmussen (1998) listed this species among five Ponto-Caspian mysids that, due to their salinity tolerance, are likely to be transported to the Great Lakes via ballast water. The related Hemimysis anomala fulfilled this prediction in 2006 (Pothoven et al. 2007). Grigorovich et al. (2003), however, identified L. benedeni as having a reduced probability of invasion due to the effects of ballast water exchange or flushing, while they classified H. anomala as having a greater likelihood of introduction. This species is currently widespread throughout the entire North Sea basin (lower Rhine River), Baltic Sea basin, and Black-Azov Sea basin (Bij de Vaate et al. 2002; Grigorovich et al. 2003), all of which sustain heavy amounts of Great Lakes shipping traffic.

Ovcarenko et al. (2006) reported that L. benedeni was largely unaffected by salinity increases up to 19 PSU and showed only about 25% mortality when exposed to 23 PSU for 24 hours. It was not until 24 hours of exposure to 34 PSU that a 100% mortality rate was observed. This high salinity tolerance was confirmed by Santagata et al. (2008), who reported 60+14% and 55+13% (mean + s.d.) survival rates for freshwater individuals exposed to full-strength (34 PSU) seawater for 48 hours in flow-through and empty-refill treatments, respectively. These results provide evidence that current ballast water control measures may not be completely effective in preventing the introduction of this species to the Great Lakes.

Status: Not established in North America, including the Great Lakes

Limnomysis benedeni has a high probability of establishment if introduced to the Great Lakes (Confidence level: High).

This species is able to survive in a relatively wide range of temperature (0–31°C) and salinity (0–14 ppt), though its minimum dissolved oxygen requirement (3.75 mg/L) is higher than that of many other freshwater invertebrates (Wittmann 2009). Limnomysis benedeni is able to tolerate a relatively wide range of pH (5.5–9.6), though it prefers slightly alkaline conditions (Wittmann 2009). All five Lakes would likely serve as suitable habitat under these physiological requirements; however, due to the relatively high oxygen demands, it may be restricted from establishing populations in portions of Lake Erie that undergo anoxic conditions. This species produces an overwintering generation in autumn that is able to survive in 0°C waters until the following spring (Wittmann 2009), making it a likely candidate to overwinter in the Great Lakes.  It is possible that this relatively high oxygen demand may interfere with its ability to overwinter in the Great Lakes.

Climatic conditions throughout the native range of this species are very similar to those experienced by the Great Lakes–a continental climate with dry summers (warm average temperatures > 10°C, coldest month < 0°C)  (Wittmann 2009). Limnomysis benedeni prefers current velocities less than 0.5 m/s (Wittmann 1995), making most of the Great Lakes suitable habitat with respect to water motion. Increased salinization as a result of climate change (Rahel and Olden 2008) will likely give this species a competitive advantage over the only Great Lakes native mysid, Mysis diluviana (salinity tolerance 0-3 ppt) (Audzijonyte and Väinölä 2005), as it is tolerant of salinities up to 14 ppt. Shorter ice cover duration and warmer water temperatures may also benefit this species by lengthening the suitable yearly breeding period.

This species is classified as an omnivore-herbivore (Gergs et al. 2008), with a non-specific food preference (Bij de Vaate et al. 2002). None of its food sources (see Ecology) are limiting within the Great Lakes. Limnomysis benedeni contributes significantly to the diets of various fish species, including perch (Bacescu 1940, 1954; Zhadin and Gerd 1961; Mordukhai-Boltovskoi 1979; Hanselmann et al. 2011; Specziár and Eros 2014), and would be be expected to be consumed by fish in the Great Lakes. However, the degree to which the establishment of L. benedeni could be prevented by predation is unclear.

Limnomysis benedeni has a history of outcompeting other species within its exotic range. Olenin et al. (2007) assessed the invasion effect of this species in the Curonian Lagoon as causing a moderate decline in abundance and reduction in range of native species. If it succeeds in invading fresh and brackish water Mediterranean tributaries, it has been predicted to outcompete the closely related genus Diamysis (Wittmann and Ariani 2000). Additionally, a loss of native macroinvertebrate species in the upper Rhine was noticed after the appearance of L. benedeni (Bernauer and Jansen 2006).

This species is classified as having a high fecundity (Bij de Vaate et al. 2002). This, together with iteroparity and multiple generations per year give L. benedeni a high reproductive potential and increase its competitive ability. A single female with fertilized eggs or larvae in the brood pouch may be sufficient for founding a new population (Wittmann 2009).

Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...


Limnomysis benedeni has the potential for moderate environmental impact if introduced to the Great Lakes.

Limnomysis benedeni is a host species of burn spot disease (Austin and Alderman 1987), a bacterial shell disease causing fungal infection of the exoskeleton and gills found in a number of crustacean taxa including crayfish.

The effect of L. benedeni invasion in the Curonian Lagoon has been a moderate decline in abundance and reduction in range of native species (Olenin et al. 2007). Moreover, Bernauer and Jansen (2006) noted a loss of native macroinvertebrate species in the upper Rhine River, Germany after the appearance of a number of invasive macroinvertebrates, including L. benedeni. Additionally, this species may have altered the freshwater food web in Switzerland (Gauer and Imesch 2008). Its impact on ecosystem functioning has been classified as moderate (i.e. weak modification of ecosystem performance and/or addition of a new, or reduction of existing, functional groups) (Olenin et al. 2007). It is predicted to outcompete the closely related genus Diamysis if it succeeds in invading fresh and brackish water Mediterranean tributaries (Wittmann and Ariani 2000). The introduction of L. benedeni in Upper Lake Constance in Europe was considered one of the possible driving forces behind the explosive invasion of the three-spined stickleback in 2013 (Gasterosteus aculeatus) due to their value as a food source for the fish (Rösch et al. 2018).

The non-native population of L. benedeni in the strongly eutrophic Curonian Lagoon is reported to be a biomass dominant component of the nektobenthic community, with major significance in modifying sediment/habitat by pelletization (Olenin and Leppäkoski 1999). According to Olenin et al. (2007), this species causes alteration to the physical habitat without reducing total habitat area.

There is little or no evidence to support that Limnomysis benedeni has the potential for significant socio-economic impacts if introduced to the Great Lakes.

According to Austin and Alderman (1987), L. benedeni is vulnerable to burn spot disease, a bacterial shell disease found in shellfish, including Oroconectes crayfish, though the frequency and severity of possible impacts on aquaculture are unknown.

Limnomysis benedeni has the potential for moderate beneficial effects if introduced to the Great Lakes.

Limnomysis benedeni is often found in the stomach of freshwater fish and has been emphasized as an important food source, particularly for foraging fish (Rezsu et al. 2006). Limnomysis benedini contains high concentrations of polyunsaturated fatty acids (PUFA) which are important for fish nutrition (FInk 2013). Additionally, increasing aquarist use of this species as fish fodder and as ornamental shrimp (Piepiorka and Walter 2006) is accompanied by increasing numbers of Internet offers for its sale (Wittmann and Ariani 2009) – though so far apparently only in Europe.

Management: Regulations (pertaining to the Great Lakes)
There are no known regulations for this species.*

*Ballast water regulations applicable to this species are currently in place to prevent the introduction of nonindigenous species to the Great Lakes via shipping. See Title 33: Code of Federal Regulations, Part 151, Subparts C and D (33 CFR 151 C) for the most recent federal ballast water regulations applying to the Great Lakes and Hudson River.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.


There are no known biological control methods for this species.

There are no known physical control methods for this species

There are no known chemical control methods for this species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

References (click for full reference list)

Author: Baker, E. and K. Dettloff

Contributing Agencies:

Revision Date: 9/8/2021

Citation for this information:
Baker, E. and K. Dettloff, 2023, Limnomysis benedeni Czerniavsky, 1882: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/8/2021, Access Date: 9/28/2023

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.