Goldfish is a small sized freshwater fish belonging to the family Cyprinidae and order Cypriniformes.
It is one of the most popular and old fish domesticated from a long time and is generally kept as an aquarium fish.
Goldfish is a member of carp family and it native and is native to East Asia.
It was first domesticated in China around thousand years ago and several new breeds have been developed.
The breeds of goldfish may vary in size, body shape, fin configuration and colouration.
The scientific name of goldfish is Carassius auratus auratus.
In ancient China many species of carps were domesticated and used as food for thousands of years.
These carps were silver to grey in colour but some developed shades of red, orange and yellow due to mutations.
During the 1620s goldfishes earned good reputation as it was believed that they bring good fortune.
It became a tradition that married men gave their wives a goldfish after completion of one year of their married life so that the coming years may be full of happiness.
Goldfishes were bred from Prussian carp in China which are the closest wild relatives of goldfish.
Some claim the goldfishes are relatives of Crucian carps.
When naturally found in nature goldfishes are olive green in colour.
Introduction of goldfishes in wild may cause harm to the native fishes.
They also bear good potential to form hybrids with other carps.
After producing three generations they revert back to their natural olive green colour.
The mutation that gave rise to domestic goldfish has been reported from other carps also like tench and common carp.
There are many varieties of domestic goldfish.
Fancy goldfish is unable to survive in the wild as its fins are brightly coloured.
Common goldfish and comet can survive in ponds.
Selective breeding over several thousands of years have resulted in the production of various shades of goldfish.
Some species can survive only in aquariums.
In 2008 world's largest goldfish was recorded from Netherlands.
It measured 19 inches in length.
They are very popular pond fishes, small, inexpensive and colourful fishes.
In the outdoor ponds they are able to survive for brief periods only.
Common goldfishes are London and Bristol shubunkins, jikin, wakin, comet and some hardier fantail goldfish which can be reared in ponds throughout the year under tropical and subtropical climates.
During winter months they become sluggish, stop eating and rest at the bottom of the pond.
They again become active in spring.
Like carps they excrete large amount of waste both in faeces and through their gills releasing toxic chemicals into water.
They are classified as cold water fishes as they can tolerate temperature range as tolerated by humans.
Temperature range plays an important role in maintaining their culture.
They produce pigments in response to light.
The skin bears chromatophores which contain pigments responsible for red, yellow or orange colours.
They prefer to feed on crustaceans, insects and other plant materials.
They do not stop eating on their accord.
Overfeeding may be fatal as it results in blocking of intestines.
When plenty of food is available they pass large amount of faecal matter due to incomplete digestion of proteins.
Goldfishes require more carbohydrates and less protein in their diets.
Behaviour of goldfishes is strongly dependent on the environment.
They have good associative learning and social learning skills.
Visual acuity helps them to differentiate between animals and humans.
They are gregarious fishes are famous for displaying schooling and feeding behaviours.
They have a compact association with humans and so are not considered threat for humans.
They have a memory span of at least three months and can differentiate between shapes, colors and sounds.
By positive reinforcement goldfishes can be trained to recognize and react other signals.
They attain sexual maturity only when enough water and right nutrition is present.
Most goldfishes breed in captivity like in pond settings.
Both male and female goldfishes chase each other before mating.
They are oviparous.
Eggs are sticky and are attached to aquatic vegetation.
Incubation period varies from 48-72 hours.
Eggs hatch into tiny individuals known fries.
Eggs hatch into tiny fries.
After living for a period of one week the fries attain the same size as that of the adults.
Like other popular fishes they are also used in mosquito control.
Some countries have banned the sale of ornamental fishes as they can affect the population build up of the native species.
Though edible, goldfishes are rarely consumed as food fishes.