File:Black 6 mouse eating.jpg
C57BL/6, female, 22 weeks of age

C57BL/6, often referred to as "C57 black 6", "C57" or "black 6" (standard abbreviation: B6), is a common inbred strain of laboratory mouse.

It is the most widely used "genetic background" for genetically modified mice for use as models of human disease. They are the most widely used and best-selling mouse strain, due to the availability of congenic strains, easy breeding, and robustness.[1]

Appearance and behavior

C57BL/6 mice have a dark brown, nearly black coat. They are more sensitive to noise and odours and are more likely to bite than the more docile laboratory strains such as BALB/c.[2] They are good breeders.[1]

Group-housed B6 mice display barbering behavior, in which the dominant mouse in a cage selectively removes hair from its subordinate cage mates. Mice that have been barbered have large bald patches on their bodies, commonly around the head, snout, and shoulders, although barbering may appear anywhere on the body. Both hair and vibrissae may be removed.[3]

C57BL/6 has many unusual characteristics that make it useful for some work and inappropriate for other: It is unusually sensitive to pain and to cold, and analgesic medications are less effective in it.[1][4] Unlike most mouse strains, it drinks alcoholic beverages voluntarily. It is more susceptible than average to morphine addiction, atherosclerosis,[citation needed] and age-related hearing loss.[5]


The C57BL/6 mouse was the second-ever mammalian species to have its entire genome published.[1]

The dark coat makes the mouse strain convenient for creating transgenic mice: it is crossed with a light-furred 129 mouse, and the desirable crosses can be easily identified by their mixed coat colors.[1]


By far the most popular laboratory rodent, the C57BL/6 mouse accounts for half to five-sixths of all rodents shipped to research laboratories from American suppliers.[1] Its overwhelming popularity is due largely to inertia: it has been widely used and widely studied, and therefore it is used even more.[1]

In 2013 C57BL/6 mice were flown into space aboard Bion-M No.1.[6]

In 2015 C57BL/6NTac females provided by Taconic Biosciences were sent to the International Space Station on SpaceX CRS-6.[7]


The inbred strain of C57BL mice was created in 1921 by C. C. Little at the Bussey Institute for Research in Applied Biology.[1] The substrain "6" was the most popular of the surviving substrains.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Engber, Daniel (17 November 2011). "The Trouble With Black-6: A tiny alcoholic takes over the lab.". 
  2. Connor, A.B. (2006). "Aurora’s Guide to Mouse Colony Management" (PDF). Cell Migration Gateway. CMC Activity Center. Retrieved 19 December 2013. 
  3. Sarna, JR; Dyck, RH; Whishaw, IQ (February 2000). "The Dalila effect: C57BL6 mice barber whiskers by plucking". Behavioural Brain Research 108 (1): 39–45. PMID 10680755. doi:10.1016/S0166-4328(99)00137-0. Retrieved 2011-01-16. 
  4. Mogil JS, Wilson SG, Bon K; Wilson; Bon; Lee; Chung; Raber; Pieper; Hain; Belknap; Hubert; Elmer; Chung; Devor et al. (March 1999). "Heritability of nociception I: responses of 11 inbred mouse strains on 12 measures of nociception". Pain 80 (1–2): 67–82. PMID 10204719. doi:10.1016/s0304-3959(98)00197-3. 
  5. Willott, James F. (April 2013). "Audition". In Crusio, Wim E.; Sluyter, Frans; Gerlai, Robert T.; Pietropaolo, Susanna. Behavioral Genetics of the Mouse: Genetics of Behavioral Phenotypes. Cambridge Handbooks in Behavioral Genetics. Cambridge, United Kingdom: Cambridge University Press. pp. 36–44. ISBN 978-1-107-03481-5. 
  6. Zak, Anatoly. "Bion (12KSM) satellite". RussianSpaceWeb. Retrieved 19 April 2013.