Cyprinus tinca Linnaeus, 1758; Cyprinus tinca auratus Bloch, 1782; Cyprinus tincaauratus Bloch, 1782; Cyprinus tincauratus Lacepède, 1803; Cyprinus tincaurea Shaw, 1804; Cyprinus zeelt Lacepède, 1803; Tinca aurea Gmelin, 1788; Tinca chrysitis Fitzinger, 1832; Tinca communis Swainson, 1839; Tinca italica Bonaparte, 1836; Tinca limosa Koch, 1840; Tinca linnei Malm, 1877; Tinca vulgaris Fleming, 1828; Tinca vulgaris cestellae Segre, 1904; Tinca vulgaris maculata Costa, 1838; green tench (Sabapathy 2014; GISD 2014)

Characteristics typically used distinguish tench include:

• Body Shape and Size:
  • Stocky, robust, and laterally-compressed body similar to carp
  • Adult can grow to 70 cm (~28 in) standard length
  • Adults can grow to 7.5 kg (16 lbs)
  • Triangular head
  • Terminal mouth with well-developed barbel at both corners of mouth
  • 96-115 scales along lateral line
• Coloration:
  • varying shades of olive-green to black on their upper body
  • a paler, golden color underside
  • red-orange eyes
• Fins:
  • 4 dorsal spines with 8-9 dorsal soft spines
  • 3-4 anal spines with 6-8 soft spines
  • Caudal fin has 19 rays with a deep and short peduncle (i.e. tail fin base)

FOOD WEB: Tench is primarily a benthic generalist feeding primarily on benthic aquatic invertebrates. Diet analysis of adult tench indicates that they will consume a wide variety of prey items from over 60 different taxa, primarily. Chromatid larvae (non-biting midges) usually make up a large part of tench diets, along with caddisflies, mayflies, beetles, dragonflies, and mollusks (Weatherley 1959; Scott and Crossman 1973; Ranta and Nuutinen 1984; Michel and Oberdorff 1995; Perrow et al. 1996; González et al. 2000; Alas et al. 2010; USFWS ERSS 2014; Bezmaternykh and Shcherbina 2018). During the early years of their life, tench primarily feed on zooplankton, with a preference for larger-bodied cladocerans. Tench will also consume plant material, some which include seeds that are viable after being ingested, and might be an important vector for plant dispersal (Boedeltje et al. 2019).

Tench mainly feed from May to September, peaking in August (Bezmaternykh and Shcherbina 2018). They are primarily crepuscular and nocturnal feeders, using their sensitive barbels to locate food items on the lake or pond bottom (Perrow et al. 1996; Bezmaternykh and Shcherbina 2018).

LIFE HISTORY: Tench have a relatively long lifespan, often reaching 10 to 15 years or more in the wild. They are known for their slow growth rate. Sexual maturity is usually achieved at around 3 to 4 years of age, depending on environmental conditions (Yilmaz 2002). Tench are oviparous, spawning during the late spring and early summer when water temperatures rise (Avlijaš et al. 2018).

Tinca tinca has a high probability of introduction to the Great Lakes (Confidence level: High).
Potential pathway(s) of introduction: Dispersal

Tench have known reproducing populations in the St. Lawrence and possibly Humber River, Ontario, both of which are connected to the Great Lakes (Avlijaš et al. 2018). In the St. Lawrence River, tench populations extend as far west as Lake Saint Francis and are separated from Lake Ontario by the Moses Saunders Dam. In October 2018, a tench was caught by a commercial fisherman in the Bay of Quinte, Lake Ontario (Avlijaš et al. 2018). An illegally stocked population in the headwaters of the Humber River was discovered in 2014 and reportedly eradicated (Avlijaš et al. 2018). The Humber River does not have any barriers to Lake Ontario.

Tench may be misidentified as other species and used as bait which could lead to unauthorized intentional release.

Tinca tinca has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: High).
Tench have high tolerance to a broad range of environmental conditions including low pH, low dissolved oxygen, and high temperatures (Sabapathy 2014; Avlijaš et al. 2018). However, they do not typically inhabit fast flowing water (Avlijaš et al. 2018). They can likely overwinter in the Great Lakes given that they have established populations in Quebec and Ontario (Avlijaš et al. 2018). Climate match analysis rates the Great Lakes region as very high (Avlijaš et al. 2018). Tench also has a broad diet (Scott and Crossman 1973; Alas 2010; Bezmaternykh and Shcherbina 2018), which means they would also likely find appropriate food sources if introduced to the Great Lakes.

However, tench were introduced throughout the United States in the 19th century, yet are only established at a fraction of these sites today (Avlijaš et al. 2018). Some observations indicate that the failure of the tench to establish may be related to a biotic interaction with centrarchids (DeVaney et al. 2009), which are also widely distributed in the Great Lakes Region.

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

Environmental	Socioeconomic

Tench may also harm native cyprinids and other benthic species through competition (Avlijaš et al. 2018).

Experimental trials showed that tench negatively impact gastropod populations, indirectly leading to increased periphyton biomass and alter physical habitat by reducing macrophyte abundance through trophic cascades (Beklioglu and Moss 1998, Avlijaš et al. 2018). Additionally, the presence of tench is predicted to disturb sediment, reduce water clarity, and disrupt trophic cascades, further affecting macrophytes and promoting epiphytic algae in the Great Lakes region (Avlijaš et al. 2018).

There is little or no evidence to support that Tinca tinca has the potential for significant Socio-Economic impacts if introduced to the Great Lakes.
Tench are not reported to pose any threat to human health, damage infrastructure, affect water quality, harm economic sectors, or inhibit recreational activity.

Tinca tinca has the potential for moderate beneficial impacts if introduced to the Great Lakes.
Tench were originally brought to the United States for use as a food and sport fish (USFWS ERSS 2014). Tench may be mixed with other rough fish for sale (Avlijaš et al. 2018). However, there is not much demand for tench, and their economic contribution is insignificant (Dumont et al. 2002, Marcogliese et al. 2009). Tench are sometimes fished recreationally, however there are already numerous sport fish established in the Great Lakes.

*Page last updated 7/05/2022. Always check federal, state/provincial, tribal and local regulations directly for the most up-to-date information.

Tench are prohibited in Michigan (324.41301), New York (6 NYCRR Part 575), Ohio (Ohio Administrative Code 1501:31-19-01), and Wisconsin (NR 40.04 C11).  Tinca tinca are prohibited in Ontario (regulatory amendments to Ontario Regulation 354/16 under the Invasive Species Act, 2015).

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

Control
    Biological
    Bass consume tench (USFWS ERSS, 2014); restricting harvest of bass in areas where tench have been collected may help to reduce their population.
   
    Physical
    Physical barriers such as dams may prevent dispersal of tench
   
    Chemical
    Piscicides such as Rotenone may be effective in managing small isolated populations of tench, however expect significant mortality in non target species.

Tench were introduced to Tasmania in the 19th century (Weatherley 1961).

DeVaney et al. (2009) performed ecological niche modeling to examine the invasion potential for Tench and three other invasive cyprinids (Common Carp Cyprinus carpio, Grass Carp Ctenopharyngodon idella, and Black Carp Mylopharyngodon piceus). All of the current established populations of Tench were in areas of predicted high suitability for this species. Interestingly, many areas where tench failed to become established or is currently extirpated (e.g., Great Lakes region) also had a moderate to high predicted suitability. DeVaney et al. (2009) attributed this potentially to negative interactions with sunfishes or unmeasured environmental factors.

Voucher specimens: Colorado (USNM 055569), Maryland (USNM 31003, 37850, 30336, 27234), Missouri (USNM 073666), New Mexico (UMMZ 118218), Virginia (USNM 30336, 31003, 37850).