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Genetic Welfare Problems of Companion Animals
An information resource for prospective pet owners
Bubble-Eye Goldfish
Bubble-Eye
Related terms: Bubble eye
Outline: Bubble-eye goldfish have been selected for dramatically protruding, fluid-filled sacs beneath each eye. These compromise behaviour and vision and are at risk of injury and infection and associated pain.
Summary of Information
(for more information click on the links below)
1. Brief description
Bubble-eye goldfish are a variety or breed of ornamental goldfish. They have large, fluid-filled sacs projecting from the bottom of each eye which can become injured and infected causing pain. They also have no dorsal fin. These abnormalities lead to the handicaps of poor swimming ability and partial blindness and the risk of physical injury, difficulty in feeding and a shortened lifespan.
2. Intensity of welfare impact
The nature and intensity of the effects of the abnormalities and their effects on behaviour and vision on the quality of life of affected fish is hard to judge (but there seems no good case for these which compromise the fish's normal biology). There is a high risk of damage to the protruding eye tissues and infection and the welfare effects of such damage and infection may be severe.
3. Duration of welfare impact
The effects on behaviour and vision are lifelong. The duration of pain if the eye tissues become damaged and infected will depend on the nature of the injury or infection and whether they progress, recur or are resolved: but may be prolonged.
4. Number of animals affected
All bubble-eye goldfish have the bubble-eye deformity.. There are no data on the proportion that develop other ‘knock-on’ problems (eg infections) as a result of the deformity.
5. Diagnosis
All bubble-eye goldfish are affected.
6. Genetics
The genes responsible for the presence of the eye sacs and the absence of the dorsal fin have not been investigated.
7. How do you know if an animal is a carrier or likely to become affected?
All bubble-eye goldfish are affected.
8. Methods and prospects for elimination of the problem
The problems can be eliminated by not breeding from animals that show this trait.
To avoid the risk of perpetuating the welfare problems associated with this condition, bubble-eye goldfish should not be purchased.
For further details about this condition, please click on the following:
(these link to items down this page)
- Clinical and pathological effects
- Intensity of welfare impact
- Duration of welfare impact
- Number of animals affected
- Diagnosis
- Genetics
- How do you know if an animal is a carrier or likely to become affected?
- Methods and prospects for elimination of the problem
- Acknowledgements
- References
1. Clinical and pathological effects
Goldfish (Carassius auratus auratus) are a domesticated form of the common carp originating in Eurasia: the Chinese Crucian carp “Gibelio” (Carassius auratus gibelio) (Komiyama et al 2009). Bubble-eye goldfish apparently emerged as a distinct type or breed of the goldfish in early 20th century China.
There are two distinct abnormalities of the bubble-eye’s conformation. The obvious one is the presence of (usually) one fluid-filled sac on each side of the head beneath each eye, sometimes called eye or periocular sacs (Wildgoose 2001). These eye sacs develop and grow throughout the fish’s life and can protrude very markedly from the head. They are filled with a clear, lymph-like fluid (Sawatari et al 2009). They serve no useful function for the fish but rather are a deformity that exists only because they are thought attractive by some people. These features give the breed its name. However, typically, bubble-eyes have another feature that leads to unacceptable welfare issues – the absence of a dorsal (back) fin. Normal fish always have a dorsal fin; as have other animals adapted to a swimming lifestyle, e.g. whales and dolphins. It functions to provide stability in the water and to prevent rolling. Goldfish without dorsal fins have slower swimming speed and acceleration, have to cope with rolling and yawing (twisting when trying to go in a straight line) compared with normal goldfish (Blake et al 2009) and thus have to expend more energy to swim.
The welfare problems suffered by these animals result from the combination of the physical presence of their eye sacs and the absence of their dorsal fins; although either of these abnormalities, by itself, would be a major welfare concern.
The presence of the sacs affects the fish’s ability to swim by increasing drag, making swimming difficult and more energy demanding. This is compounded by the absence of a dorsal fin. These abnormalities lead to an inability to avoid obstacles, an inability to search for food and to swim against currents so that fish are often swept into water outflow devices and trapped. The fish often appear “weighed-down” by their sacs, being seen at the bottom of the aquarium in a position with their heads lower than their bodies.
The physical presence of the sacs makes the fish partially blind. They cannot see below them or, for example, food directly in front, near their mouths.
The sacs are easily damaged. They are quite fragile but when combined with the fish’s poor swimming abilities and partial blindness trauma to the sacs is inevitably common. The sac wounds may heal or they may become infected causing pain and possibly leading to death.
All these factors mean that bubble-eyes can only be housed in minimalistic, bare aquaria that lack objects that they could bump or be swept into that might cause physical damage. They also should not be housed with fish with more normal anatomy that would always out-compete them by being able to see and swim to food before the bubble-eyes can get there. Biting at the sacs by other fish is also a potential cause of trauma. Housing bubble-eyes with similarly handicapped fish such as celestials has been recommended.
Animals with such severe conformational defects not surprising have shortened lives. They are said to have a life span approximately half that of goldfish with a normal shape.
There are no treatments for this condition; the handicap has to be managed by adapting the fish’s environment.
2. Intensity of welfare impact
Genetic modification by selective breeding of fish can cause major welfare problems (Kolle & Hoffmann 1997). It seems reasonable to propose that this handicap causes serious welfare problems as the animal is unable to behave normally and its vision is compromised. There is a high risk of injury to the sacs and injuries and any infections that may result are likely to cause pain and may lead to death.
3. Duration of welfare impact
The effects of the bubble-eye abnormality on behaviour and vision are lifelong, as are the effects on behaviour of the absence of the dorsal fin. The duration of pain if the eye tissues become damaged and infected will depend on the nature of the injury or infection and whether they progress, recur or are resolved. In mild cases the effects may be short (eg days) but in other cases, pain may be prolonged (eg weeks) and there could be repeated bouts.
4. Number of animals affected
All bubble-eye goldfish have the bubble-eye deformity. There are no data, as far as we are aware, on the proportion that develop ‘knock-on’ problems (injuries and infections) as a result of the deformity, but the literature suggests that these are not uncommon.
5. Diagnosis
All animals of this breed have the bubble-eye abnormality. The diagnosis of injuries and infections will depend on careful examination of the fish.
6. Genetics
The genetic defects that cause the bubble eye and the dorsal fin absence have not been discovered but it is likely that they are similar to those also found in the celestial goldfish. The loss of the fin and the presence of the eye sacs probably are independent with the loss of the fin having occurred historically prior to the eye defect (Komiyama et al 2009).
7. How do you know if an animal is a carrier or likely to become affected?
All bubble-eye individuals are affected.
8. Methods and prospects for elimination of the problem
For welfare reasons, it seems reasonable to propose that the breed of bubble-eye goldfish should not be perpetuated. Prospective goldfish owners should avoid purchase of these fish.
9. Acknowledgements
UFAW is grateful to Rosie Godfrey BVetMed MRCVS and David Godfrey BVetMed FRCVS for their work in compiling this section.
We are most grateful to all those who have helped in collecting information for, and with drafting, this site, including David Godfrey, Rosie Godfrey, Carol Fowler, Hazel Bentall, Alex German and all those acknowledged at the description of each condition.
Many images of the breeds have been taken from relevant pages on Wikipedia, and for these, the license under which they can be used and the person who supplied the picture, can be found by double clicking on the image itself.
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 Wochenschrift 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. 2009 430: 5-11
Sawatari E, Hashimoto H, Matsumura T, Iwata Y, Yamamoto N, Yokoyama Y and Wakamatsu Y (2009) Cell growth-promoting activity of fluid from eye sacs of the bubble-eye goldfish (Carassius auratus). Zoological Science 26: 254-8
Wildgoose WH (2001) Taking the plunge: treating pet fish. In Practice 23: 220-227
The following websites giving unreferreed advice about care of bubble-eye goldfish were accessed on 1st October 2010
http://www.allabout-aquariumfish.com/2010/04/special-bubble-eye-goldfish-care.html
http://www.desktopgoldfish.com/goldfish-types.php?func=fishDetail&fish=Bubble%20Eye
http://www.fishkeeping.co.uk/modules/caresheets/caresheet.php?caresheetID=85
http://www.goldfishtypes.net/bubble-eye-goldfish/
http://www.aquaticcommunity.com/goldfish/bubbleeye.php
http://www.goldfish-as-pets.com/bubble-eye-goldfish.html
© UFAW 2011
Credit for main photo above:
http://commons.wikimedia.org/wiki/File%3AGoldfish_Bubble_Eye.jpg
By Lerdsuwa (Own photo (400D + 50/1.4)) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
