Genetic Welfare Problems of Companion Animals

An information resource for prospective pet owners

Lionhead Goldfish

Lionhead Goldfish

Absent Dorsal Fin

Outline: Lionhead goldfish have no dorsal fin. As a result, their control and agility in the water is compromised. This would be likely to be a serious handicap in the wild but it is difficult to assess the impact of this on their welfare in a captive environment.


Summary of Information

(for more information click on the links below)

1. Brief description

All normal fish have a dorsal fin. This fin functions to provide stability in the water and to prevent rolling. Some strains of goldfish have been developed in which one or more fins are absent or deformed. Goldfish without dorsal fins have been shown to have slower swimming speed, slower acceleration and more inefficient locomotion than normal goldfish and have to cope with the tendency to roll to the side during movement or at rest and with having less directional stability (Blake et al 2009).

2. Intensity of welfare impact

Some genetic modifications of fish by selective breeding can cause major welfare problems (Kolle & Hoffmann 1997). In this case, the welfare effects of the absence of a dorsal fin are difficult to assess. Affected fish have reduced control over their position and movement in the water. This would be likely to be a serious handicap in the wild but the effects on quality of life in a captive environment are unclear. Research is needed in this area. 

3. Duration of welfare impact

The dorsal fin is absent at birth and throughout life.

4. Number of animals affected

All fish of this breed are affected, as the absence of the dorsal fin is a breed characteristic.

5. Diagnosis

The absence of the dorsal fin is obvious.

6. Genetics

The condition certainly has a genetic basis but the gene or genes involved have not been determined. We are unaware of information on the patter of inheritance.

7. How do you know if an animal is a carrier or likely to become affected?

All fish of this breed are affected, as the absence of the dorsal fin is a breed characteristic.

8. Methods and prospects for elimination of the problem

The problem could be eliminated by not breeding from animals that show this trait.


For further details about this condition, please click on the following:
(these link to items down this page)


1. Clinical and pathological effects

Goldfish (Carassius auratus auratus) are a domesticated form of a common Chinese carp, the Chinese Crucian carp “Gibelio” (Carassius auratus gibelio) (Komiyama et al 2009). Egg goldfish may have been the first type to be bred for the absence of a dorsal fin, perhaps 700 years ago. Lionhead goldfish with this characteristic were bred in China and Japan prior to the 17th century.

All normal fish have a dorsal fin. This fin provides stability in the water and prevents rolling. Goldfish without dorsal fins have slower swimming speed, slower acceleration, and swim less efficiently than normal goldfish. They also have to cope with the tendency to roll to the side during movement or at rest and with reduced directional stability (Blake et al 2009).

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2. Intensity of welfare impact

Some genetic modifications of fish by selective breeding can cause major welfare problems (Kolle & Hoffmann 1997). In this case, the welfare effects of the absence of a dorsal fin are difficult to assess. Affected fish have reduced control over their position and movement in the water. This would be likely to be a serious handicap in the wild but the effects on quality of life in a captive environment are unclear. Research is needed in this area.

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3. Duration of welfare impact

The dorsal fin is absent at birth and throughout life.

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4. Number of animals affected

All fish of this breed are affected, as the absence of the dorsal fin is a breed characteristic.

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5. Diagnosis

The absence of the fin is obvious.

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6. Genetics

The condition certainly has a genetic basis but the gene or genes involved have not been determined. We are unaware of information on the patter of inheritance.

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7. How do you know if an animal is a carrier or likely to become affected?

All fish of this breed are affected, as the absence of the dorsal fin is a breed characteristic.

Return to top

8. Methods and prospects for elimination of the problem

The problem could be eliminated by not breeding from animals that show this trait.

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9. Acknowledgements

UFAW is grateful to Rosie Godfrey BVetMed MRCVS and David Godfrey BVetMed FRCVS for their work in compiling this section.

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10. References

Blake RW, Li J and Chan KHS (2009) Swimming in four goldfish Carassius auratus morphotypes: understanding functional design and performance employing artificially selected forms. Journal of Fish Biology 75: 591–617

Kolle P and Hoffmann R (1997) Qualzuchten bei Fischen [Excessive breeding in ornamental fish]. Deutsche Tierarztliche Wochenschrif 104: 74-75

Komiyama T, Kobayashi H, Tateno Y, Inoko H, Gojobori T and Ikeo K (2009) An evolutionary origin and selection process of goldfish. Gene 430: 5-11

The following website giving unreferreed advice about care of goldfish was accessed on 24th September 2011

http://www.allabout-aquariumfish.com/2008/04/goldfish-varieties-ranchu.html

http://www.aquaticcommunity.com/goldfish/lionhead.php

© UFAW 2012


Credit for main photo above:

http://depositphotos.com/2587275/stock-photo-fancy-goldfish.html ©Depositphotos.com/aremafoto