A mirror carp, or Cyprinus carpio, is a large, freshwater fish that is closely related to the common carp, and is very similar in appearance to several other types of carp. These fish can grow in excess of 3.5 feet (1 meter) in length and have been known to live up to 60 years of age, although 20 years tends to be the average life span. Commonly weighing around 20 pounds (9 kilograms), the large size of these fish mean they are unsuitable for small ponds or waterways, as they need a great deal of space and a plentiful food supply. It has a long history, believed to have first been bred around 1300, as one of the earliest documented British and European attempts at deliberate selective breeding of fish. Popular with experienced anglers, the mirror carp is very common across much of Europe and the British Isles.
Mirror carp live in large, cool to temperate bodies of fresh water, being among the most abundant large, freshwater fish across the United Kingdom and much of Eurasia. Closely related to the common carp, the mirror carp is very similar in appearance to this fish, as well as the leather carp, as both are variations or sub-species of the common carp. It is believed to have been selectively bred from the common carp by monks and introduced as a valuable food source some time during the 1300s, which resulted in large, fleshy fish with very few scales making it an excellent and easy-to-prepare food.
Mirror carp are distinguishable from other types of carp because of their distinctive scale patterns which are unique to each individual fish. They have very few scales, and those that are present are usually very large and reflective, hence the name mirror carp. Many of the larger specimens have been named based on their coloring and scale patterns. Leather carp are sometimes mistaken for mirror carps by inexperienced anglers, though the most obvious difference is that these fish generally have no scales, and if a few scales are present they are small, insignificant, and not reflective. Common carp are easily distinguishable from the leather and mirror varieties because they are fully-scaled, which are small and uniform over the entire body.