Fish Farm UK
("Home of Staffordshire 'Supa' Carp")
"The Tench or Doctor Fish (Tinca tinca) is a freshwater and brackish water fish of the cyprinid family found throughout Eurasia from Western Europe into Asia. It normally inhabits slow-moving freshwater habitats, particularly lakes and lowland rivers.
"The Tench is most often found in still waters with a clay or muddy substrate and abundant vegetation. This species is rare in clear waters across stony ground and is absent altogether from fast-flowing streams. It tolerates water with a low oxygen concentration, even being found in waters where Carp cannot survive. Tench feed mostly at night on algae and benthic invertebrates of various kinds that they root up from the bottom.
"Breeding takes place in shallow water usually among aquatic plants where the sticky green eggs can be deposited. Spawning usually occurs in summer and as many as three hundred thousand eggs may be produced. Growth is rapid and fish may reach a weight of 0.11 kg (0.25lb) within the first year.
"Tench have a stocky, carp-like shape, olive-green skin, darker above and almost golden below. The caudal fin is square in shape. The other fins are distinctly rounded in shape. The mouth is rather narrow and provided at each corner with a very small barbel...."
The tench isn't likely to be in the news. This unassuming fish doesn't shoot members of Congress, or occupy Wall Street. Not that any fish are likely to do that sort of thing.
It isn't endangered.
The tench isn't even particularly pushy. Which, applying the "nice guys finish last" principle, should have doomed it to extinction.
So why is this humble fish so successful?
The tench isn't one of your delicate critters. It will survive conditions that would kill a carp. And that's saying something.
Heat, Cold, Salt, and the Tenacious Tench...Tench can survive water temperatures as high as 30 to 35°C [86° to 95° in Fahreneheit], oxygen concentrations less than 1 ppm, and salinities up to 12 mg/1. Although tench from northern Europe can apparently withstand temperatures close to freezing, California tench, being descended from south European populations, may not be able to withstand such low temperature. The optimum temperatures for growth seem to be between 12 and 30°C.
"Tench are rather sluggish in their movements and are not very aggressive towards other tench or towards other fishes (Sterba, 1959), earning them the reputation of 'Physician of Fishes' (Walton, 1653)..."
("Inland Fishes of California," Peter B. Moyle, (2002), via Google Books and University of California Press, page 210)
Tench: a California fish? This European import is in North America, too. So, is it an "invasive species?" That's a good question: but apparently, not. Not in the 'beware the tench' sense, anyway.
Doctor Fish Gets Around"Tinca tinca"
USGS (United States Geological Service)
"...Distinguishing characteristics were given in Berg (1949), Scott and Crossman (1973), Muus and Dahlstrom (1978), Wheeler (1978), and Page and Burr (1991). Identification keys that include this species and photographs or illustrations were provided in a few published state fish books (e.g., Whitworth et al. 1968; Moyle 2002; Wydoski and Whitney 1979; Woodling 1985; Bond 1994). A name used in some of the early literature for this species is Tinca vulgaris.
"Size: 84 cm.
"Native Range: Most of Europe, including the British Isles, and parts of western Asia (Berg 1949)...."
"...States in which this species has been stocked or reported include Alabama (Baughman 1947); Arizona (Baughman 1947; Courtenay et al. 1991); Arkansas (Baughman 1947); California (Shapovalov 1944; Kimsey and Fisk 1964; Skinner 1972; Moyle 1976a; Wydoski and Whitney 1979; Courtenay et al. 1984, 1991; Dill and Cordone 1997); Colorado...."
Briefly, it's in 38 states. That the USGS knows of.
"...In the 1940s this species was reported to be a nuisance because of high abundance in certain parts of Maryland and Idaho (Baughman 1947). The diet consists mainly of aquatic insect larvae and molluscs (Scott and Crossman 1973). Moyle (1976a) considered it a potential competitor for food with sport fishes and native cyprinids...."
A cyprinid isn't a space alien from Star Wars. It's what ichthyologists call "soft-finned mainly freshwater fishes typically having toothless jaws and cycloid scales." (Princeton's WordNet)
Interestingly, "ichthyologist" is a word, but "ichtheologist" apparently isn't. That'd be someone who studies the worship of iches. Which is spelled itches, and that's another topic.
Tench: More Than Just a FishHere's a few of the world's Tenches, past and present:
- John Tench
- An actor from North America
- Tench (SS-417)
- U. S. Navy Submarine
- Artist on DeviantArt.com
Other fishy posts:
- "Save the - Goldfish?!"
(June 16, 2011)
- "Aerators in Minnesota Lakes: Good for Fish; For People, Not So Much"
(January 6, 2011)
- "(Some of) Minnesota's Fishing Seasons Open"
(May 15, 2010)
- "Piscatorial Pursuits - It's Not What You May Think"
(February 27, 2010)
- "Family and Fishing: a Personal Blog"
(August 30, 2007)