Biology of Goldfish

Amita Sarkar and Bhavna Upadhyay

Department of Zoology,Agra college,Agra(India)282001

Introduction

The goldfish (Carassiusauratus)isa freshwaterfish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish. Goldfish are often underrated in the aquarium and petindustry.[1] It has been estimated that a third of all fish sales in world are goldfish. These beautiful, hardy fish are usually the ones that launch people into the hobby. We have a responsibility to ensure every new fish keeper is a successful one. This is important to the industry, to your business, to the hobbyist and of course to the fish.[2]

Origin

In ancient China, various species of carp (collectively known as Asian carps) were domesticated and have been reared as food fish for thousands of years. Some of these normally gray or silver species have a tendency to produce red, orange or yellow color mutations; this was first recorded in the Jin Dynasty (265—420).[3] During the Tang Dynasty (618—907), it was popular to raise carp in ornamental ponds and watergardens. A natural genetic mutation produced gold (actually yellowish orange) rather than silver coloration. People began to breed the gold variety instead of the silver variety, keeping them in ponds or other bodies of water. On special occasions at which guests were expected they would be moved to a much smaller container for display.[4]

Behavior

In the wild, the diet of goldfish consists of crustaceans, insects, and various plant matter. Like most fish, they are opportunistic feeders and do not stop eating on their own accord.[5] Overfeeding can be deleterious to their health, typically by blocking the intestines. This happens most often with selectively bred goldfish, which have a convoluted intestinal tract.[6] When excess food is available, they produce more waste and feces, partly due to incomplete protein digestion. Overfeeding can sometimes be diagnosed by observing feces trailing from the fish's cloaca.

Feeding

Goldfish-specific food has less protein and more carbohydrate than conventional fish food. It is sold in two consistencies, flakes that float and pellets that sink. Enthusiasts may supplement this diet with shelled peas (with outer skins removed), blanched green leafy vegetables, and bloodworms. Young goldfish benefit from the addition of brine shrimp to their diet.[7] As with all animals, goldfish preferences vary. A good staple food for goldfish in shops is floating granules. The small size is the best, as this assures all fish get their fare share. Feeding floating granules, two or three times a day, in the right quantities is one of the major factors in keeping goldfish healthy and active.[8] A frozen "vegetable diet" is good, but duckweed is better, it is very rich in vitamin C, brings out the fish colour and increases resistance to disease.[9] If goldfish tanks are heavily stocked we must keep the quantity of food down at each feed and carry out regular partial water changes.[10]

Goldfish may only grow to sexual maturity with enough water and the right nutrition. Most goldfish breed in captivity, particularly in pond settings.[11] Breeding usually happens after a significant temperature change, often in spring. Males chase females, prompting them to release their eggs by bumping and nudging them. A pregnant goldfish is called a "twit".[12]

Goldfish, like all cyprinids, are egg-layers. Their eggs are adhesive and attach to aquatic vegetation, typically dense plants such as Cabomba or Elodea or a spawning mop. The eggs hatch within 48 to 72 hours.[13]

Within a week or so, the fry begins to assume its final shape, although a year may pass before they develop a mature goldfish color; until then they are a metallic brown like their wild ancestors. In their first weeks of life, the fry grow quickly, an adaptation born of the high risk of getting devoured by the adult goldfish (or other fish and insects) in their environment.[14]

Some highly bred goldfish can no longer breed naturally due to their altered shape. The artificial breeding method called "hand stripping" can assist nature, but can harm the fish if not done correctly. In captivity, adults may also eat young that they encounter.[15]

Goldfish can only remain healthy if the water quality is good and they are fed properly. Other than these factors, the most common health problem of goldfish is skin parasites.[7] These ubiquitous creatures keep turning up as if from nowhere. It is important to learn about them as described in the articles on skin flukes and slimy skin disease. Healthy goldfish are a pleasure to have. They should hold their fins erect, have shiny lustrous skin and eagerly charge at their food. You should not be satisfied with your fish unless they act in this way.[2]

The goldfish is thought to be the first foreign fish species introduced to North America (DeKay 1842; Courtenay et al. 1984). In the United States, large numbers are cultured as bait and as forage for sport fishes, as well as for the production of young fish that are then sold in the aquarium trade, mostly as live food (i.e., feeder fish) for carnivorous ornamental fishes. Although brightly-colored forms popular in the aquarium trade are occasionally taken in North American waters, the surviving progeny of these colorful individuals typically are the natural, cryptic olive-green coloration, partly as a result of selective predation by other animals. In nature, goldfish often hybridize with common carp Cyprinus carpio producing reproductively fertile offspring; cross fertilization and back-crossing is common in some areas, for instance polluted habitats, and in such places hybrid offspring may outnumber the parent species (Trautman 1981; Page and Burr 1991). Goldfish grow rapidly and thus are limited in their usefulness as a forage fish. The use of goldfish as baitfish is prohibited in some states. Detailed background information on the occurrence of this species in the United States was provided by Becker (1983). Knapp (1953) stated that this species is used as a hardy bait fish in many areas or crossed with carp for the same purpose. He reported that a population of these hybrids was found in Buffalo Lake, Randall County, in the Texas panhandle. In their summary table, Bailey and Smith (1981) indicated that Carassius auratus is widely distributed in the Great Lakes basin.

References 

1. Alexander, S. 2003. Goldfish become occupying force. SunSpote.net (Baltimore Sun).

2. Associated Press. 2004. Dumped goldfish blamed for killing bass in Ind. Chicago Sun-Times. July 6, 2004.

3. Bailey, R. M. and M. O. Allum. 1962. Fishes of South Dakota. Miscellaneous Publications of the Museum of Zoology, University of Michigan, Ann Arbor, MI 119:1-131.

4. Trautman, M. B. 1981. The Fishes of Ohio. Ohio State University Press, Columbus, OH.

5. Bailey, R. M. and G. R. Smith. 1981. Origin and geography of the fish fauna of the Laurentain Great Lakes basin. Canadian Journal of Fisheries and Aquatic Science 38:1539-1561

6. Swift, C. C., T. R. Haglund, M. Ruiz, and R. N. Fisher. 1993. The status and distribution of the freshwater fishes of southern California. Bulletin of the Southern California Academy of Science 92(3):101-167.

7. Baxter, G. T., and J. R. Simon. 1970. Wyoming fishes. Wyoming Game and Fish Department Bulletin 4, Cheyenne, WY. 168 pp.

8. Bean, T. H. 1903. Catalogue of the Fishes of New York. New York State Museum Bulletin 60, Zoology 9. University of the State of New York Bulletin 278. 784 pp.

9. Smartt, Joseph (2001). Goldfish varieties and genetics: A handbook for breeders. Oxford: Blackwell Science. pp. 21. 

10. Affleck, R.J. (1952) The nacreous (mottled) group of the goldfish (Carassius auratus L.) with an analysis of the colours seen in thes fish. Australian Journal of Marine and Freshwater Research, 3, 126—139.

11. Affleck, R.J. (1960) The embryology of the goldfish, Carassius auratus L. with notes on domesticated varieties. PhD thesis, Birkbeck College, University of London.

12. Virginia Department of Game and Inland Fisheries. 2004. Snakehead found in Virginia waters. US Newswire. Available at URL http://releases.usnewswire.com/GetRelease.asp?id=174-051020045/11/2004. May 10, 2004.

13. Walker, R. M. and P. H. Johansen.  1977.  Anaerobic metabolism in goldfish, Carassius auratus.  Canadian Journal of Zoology Vol. 55, No. 8, pp. 1304-1311.

14. Propst, D. L., and C. A. Carlson. 1986. The distribution and status of warmwater fishes in the Platte River drainage, Colorado. Southwestern Naturalist 31(2):149-167.

15. Raasch, M. S., and V. L. Altemus, Sr. 1991. Delaware's freshwater and brackish water fishes - a popular account. Delaware State College for the Study of Del-Mar-Va Habitats and the Society of Natural History of Delaware. 166 pp.