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Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice

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Abstract

In veterinary practice, buoyancy disorders are common in goldfish, often having a sudden onset and present floating at the surface or lying on the bottom. Fifty eight affected fish were examined in detail over a period of 11.5 years, of which 47 were goldfish: there were almost equal numbers of short-bodied and long-bodied goldfish. In many cases, there were no external lesions and no consistent environmental factors could be identified. Radiography was performed in 49 fish and proved the most useful investigative approach. Several radiographic abnormalities were found in goldfish including over-inflation (44%), displacement (22%), fluid accumulation(12%) and rupture (2%) of the swim bladder and intestinal tympany (6%). Post mortem and histological examinations were performed on 35 goldfish: findings included systemic granulomatous disease (23%), abnormal fluid in the swim bladder (23%), polycystic kidney disease (17%) and several other internal diseases (20%). However, 17% of goldfish had no identifiable pathology and no consistent radiographic features. Pathological findings in other species were varied and only rupture of the swim bladder in orfe and a renal tumour in oscars were significant. Most cases were euthanased on initial examination due to advanced disease but a quarter were treated conservatively. There was a very poor response to treatment and several environmental, medical and surgical approaches are discussed. (PDF) Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice. Available from: https://www.researchgate.net/publication/301731661_Buoyancy_disorders_of_ornamental_fish_a_review_of_cases_seen_in_veterinary_practice [accessed Mar 17 2022].
21 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 22
Oisín Naughton is a Scientific Technical Officer with the Marine Institute,
co-ordinating an inter-regional Coastal Zone Management project under
the AquaReg programme. He is also involved with the National Sea Lice
Monitoring programme and management initiatives in the aquaculture sec-
tor. Oisín studied Aquaculture and Applied Aquatic Sciences in the Galway-
Mayo Institute of Technology, and undertook a B.Sc. (Hons) degree in Marine
Science at the National University of Ireland, Galway. He also holds a M.Sc.
in Zoology from the National University of Ireland, Galway in 2001.
David Tierney is a director of Fulmar Ecological Services, a company offer-
ing aquatic and terrestrial monitoring surveys, species identification and
data analysis. He worked as a member of the National Sea Lice Monitoring
team in the Marine Institute from March 2003 to December 2004. He
graduated with a B.Sc. (Hons) in Zoology in 1996 and also holds a PhD in
Zoology, both from the National University of Ireland, Galway.
Frank Kane is a member of the National Sea Lice Monitoring team in the
Marine Institute, and has held this position for the past four years. Frank
studied Aquaculture and Applied Aquatic Sciences in the Galway-Mayo
Institute of Technology. He also undertook a B.Sc. degree in Applied Marine
Biology in Heriot-Watt University in Edinburgh.
Dr. Lorraine Copley is a Post-doctoral Scientist with the University College
Dublin, researching vaccines for sea lice on salmonids. She completed a
three-year postdoctoral research programme on sea lice biology and inter-
actions at Galway-Mayo Institute of Technology in January 2006. Prior to
this she was employed as a member of the National Sea Lice Monitoring
team at the Marine Institute. Dr. Copley completed a PhD degree in 1999, a
Masters Qualifier in 1995 and a B.Sc. degree in 1993, all in Zoology at the
National University of Ireland, Galway.
Pauline O’Donohoe is the manager of the National Sea Lice Monitoring
Programme run by the Marine Institute and has held this position since
January 2001. She is at present completing her M.Sc. degree at the Galway-
Mayo Institute of Technology. Pauline graduated with a Diploma in Aquatic
Science from GMIT and holds a B.Sc. (Hons) degree in Marine Science from
the National University of Ireland, Galway.
Buoyancy disorders of ornamental fish: a
review of cases seen in veterinary practice
William H Wildgoose
655 High Road, Leyton, London E10 6RA
Abstract
In veterinary practice, buoyancy disorders are common in goldfish, often
having a sudden onset and present floating at the surface or lying on the
bottom. Fifty eight affected fish were examined in detail over a period of
11.5 years, of which 47 were goldfish: there were almost equal numbers
of short-bodied and long-bodied goldfish. In many cases, there were no
external lesions and no consistent environmental factors could be identified.
Radiography was performed in 49 fish and proved the most useful investiga-
tive approach. Several radiographic abnormalities were found in goldfish
including over-inflation (44%), displacement (22%), fluid accumulation
(12%) and rupture (2%) of the swim bladder and intestinal tympany (6%).
Post mortem and histological examinations were performed on 35 goldfish:
findings included systemic granulomatous disease (23%), abnormal fluid
in the swim bladder (23%), polycystic kidney disease (17%) and several
other internal diseases (20%). However, 17% of goldfish had no identifiable
pathology and no consistent radiographic features. Pathological findings
in other species were varied and only rupture of the swim bladder in orfe
and a renal tumour in oscars were significant. Most cases were euthanased
on initial examination due to advanced disease but a quarter were treated
conservatively. There was a very poor response to treatment and several
environmental, medical and surgical approaches are discussed.
In fish, buoyancy is controlled by the amount and distribution of gas within
the body. This is primarily enclosed within a gas-filled buoyancy organ, the
swim bladder. In some fish, physostomes, there is a patent duct that connects
the swim bladder to the anterior oesophagus, which permits air to be swal-
lowed and forced into the swim bladder. In other fish, physoclists, there is
no patent connection and the swim bladder is inflated by the release of gas
from arterial blood by a vascular rete in the wall of the swim bladder: this
also occurs in some physostomes.
Lice infestation pressures on farmed Atlantic salmon smolts (Salmo salar Linnaeus)
in the west of Ireland following a SLICE® (0.2% emamectin benzoate) treatment PROCEEDINGS Fish Veterinary Journal (2007) (9) 22–37
23 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 24
Buoyancy disorders are common in ornamental fish and goldfish (Carassius
auratus) in particular (Lewbart 2000). Affected fish often present following
a sudden onset and are found lying on the bottom of the tank or pond, or
floating at the surface. Most are solitary cases and they often deteriorate due
to skin damage through desiccation from exposure to air if at the surface or
trauma from contact with the substrate. Few cases ever improve but despite
the poor prognosis owners often want some investigation and treatment,
particularly if they are emotionally attached to their pet. There are very few
references in the scientific literature. Tanaka and others (1998) investigated
buoyancy disorders in goldfish and there are several individual case reports
(Tocidlowski and Harms 1998, Hobbie and others 2002, Britt and others
2005, Lewbart and others 2005, Matysczak 2005) and a brief discussion of
the subject (Reyes 2005). However, there is much comment and speculation
in the hobby literature (Andrews and others 2002) and on several Internet
web sites, which most call ‘swim bladder disease’. Poor genetics, poor water
quality, poor nutrition, a rapid drop in water temperature and constipation are
often cited as the underlying cause.
This paper reviews cases investigated by the author and several aspects relat-
ing to the environment, clinical history and pathology were examined in an
attempt to find some common factors.
Materials and methods
Fifty eight fish exhibiting abnormal buoyancy were examined between
May 1994 and December 2005. Cases were recorded following a routine
investigation of the clinical history and physical examination under anaes-
thesia using tricaine methane sulphonate (MS222®, Sandoz). Radiographs
were taken in 49 cases, most of which were taken in the second half of the
study period after the author had developed a good radiographic technique.
Ultrasonography was performed in only a few cases. Some fish (26%) were
given treatment at the owner’s request, most of which subsequently died and
were unavailable for further investigations. Fish were euthanased with an
overdose of tricaine methane sulphonate. Post mortem examinations were
carried out immediately on most fish and routine samples of several tissues
including the brain were sent for histological examination.
Clinical results
Records over a four year period to December 2005 indicated that 13.5%
of phone calls from fish keepers involved buoyancy disorders. About 25%
of these were presented for examination in contrast to 10% that present
with other fish health problems. In the 11.5 year study period, 58 cases of
abnormal buoyancy were examined and all except two were solitary cases.
Of these, 81% were goldfish, 5% orfe (Leuciscus idus), 3% koi (Cyprinus
carpio), a few tropical freshwater species and one marine porcupine puffer
(fam. Diodontidae). In practice, the author mainly sees freshwater coldwater
species such as goldfish, koi, carp and orfe in fairly equal numbers. The
significantly higher percentage of goldfish confirms that this species is par-
ticularly susceptible to buoyancy disorders.
Goldfish were grouped according to body length for this review (Fig 1).
Radiographically, there is marked compression of the vertebrae in the area
dorsal to the body cavity which results in shortening of the body length and
rotund body shape in some varieties of fancy goldfish (Fig 2). The long-
bodied varieties (51%) consisted solely of common goldfish and comet-tailed
goldfish (Fig 3). The short-bodied varieties (49%) included orandas, fantails,
ranchus, black moors and a few other exotic varieties. The distribution of
varieties affected may be influenced by the popularity of those kept by
hobbyists rather than an increased susceptibility to buoyancy disorders.
Most affected goldfish came from indoor aquaria (77%), primarily because
the short-bodied fancy varieties are not suitable for outdoor ponds. The age
of affected goldfish ranged from 6 months to 17 years (median 3.5 years).
The duration of clinical signs prior to examination ranged from 12 hours
to 5.5 years (median 21 days). Where post mortem examinations were
performed (35 goldfish), 46% were female and 37% were male: it was not
possible to determine the sex in the remaining cases.
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice W.Wildgoose
FIG 1: Different varieties of fancy goldfish presented with buoyancy disorders
Long-bodied goldfish Short-bodied goldfish
38% Comet-tailed goldfish 17% Oranda
13% Common goldfish 15% Fantail
13% Black moor
4% Ranchu
25 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 26
Clinically, buoyancy disorders present with abnormal position in the water
column and abnormal body posture. Twice as many goldfish cases were on
the bottom (45%) (negative buoyancy) than were floating at the top (21%)
(positive buoyancy, Fig 4), and these fish sank to the bottom when not
actively swimming. Most fish exhibited varying degrees of listing or rolling
to one side (72%), with half of them being completely upside down. Some
fish rotated back to their original position when rolled over onto the other
side. Only a small number of goldfish had abnormal pitch, most of which
were ‘head down’ in the water (13%). In many cases, there was a combina-
tion of abnormal pitch and listing, particularly in the short-bodied varieties.
Only a few fish exhibited circling behaviour or abnormal swimming patterns
and these had granulomas in the cranial cavity.
Clinical examination of affected fish was often unrewarding, with few
exhibiting any clinical signs other than abnormal posture. In some, there was
abdominal swelling and this was often asymmetrical: affected goldfish usu-
ally had polycystic kidneys or ‘kidney enlargement disease’ and oscars had
a renal tumour. Some fish exhibited exophthalmos, particularly if they had
systemic disease and in one case extensive granulomata were found behind
the globe of one eye. Hyphaema and generalised hyperaemia with engorged
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice W.Wildgoose
FIG 2: Radiograph of a short-bodied goldfish (oranda) showing marked compression
of the vertebrae dorsal to the body cavity. This fish had an enlarged ovary full
of eggs. Bar = 1 cm
FIG 3: Radiograph of a long-bodied goldfish (comet-tailed) showing the normal
shape and position of the two-chambered swim bladder. Bar = 1 cm
FIG 4: A fancy variety of goldfish (oranda) presenting with excessive positive buoy-
ancy and floating upside down at the surface. Radiographically, this fish had
an over-inflated swim bladder.
27 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 28
blood vessels in the fins or skin was sometimes seen. In a few fish that listed
permanently to one side, the upper eye was dorsally rotated. In general, clini-
cal signs were of limited value in determining the underlying pathology.
Diagnostic imaging
Radiography proved the most useful non-lethal method of investigating
cases and clearly demonstrated the distribution of gas and space-occupying
lesions within the body cavity. The procedure requires only brief anaesthesia
to remove the fish from water and utilizes standard radiographic equipment
and techniques. The radiographic appearance of the swim bladder varies
slightly between the long- and short-bodied varieties of goldfish and the
posterior chamber is often much smaller or non-existent in the latter. A hori-
zontal beam view is useful where there is partial filling of the swim bladder
with fluid. Contrast radiography using barium or other radio-opaque media
given by gavage can be used to delineate the intestinal tract. Although ultra-
sonography has limited use when examining the swim bladder and kidney, it
was very useful for identifying diseases of the other abdominal organs and
polycystic kidneys.
Several radiographic abnormalities were identified in fish with buoyancy
disorders.
Over-inflation of the swim bladder
In goldfish, the most common abnormality was over-inflation of the swim
bladder (44%) although in some cases this was difficult to assess because of
the variable appearance of the posterior chamber in the different varieties of
goldfish (Fig 5). In oscars (Astronotus ocellatus), a South American tropi-
cal cichlid, renal papillary cystadenomas are common and cause abdominal
swelling in the posterior part of the body cavity (Gumpenberger and others
2004, Wildgoose 2004). In two of the five oscars with this renal tumour seen
by the author there was excessive positive buoyancy resulting from signifi-
cant over-inflation of the thin membranous swim bladder (Figs 6 & 7).
Displacement of the swim bladder
In goldfish, the posterior chamber was displaced in 22% of cases. The anterior
chamber of the swim bladder has a thick tunica externa and is firmly attached
to a bony vertebral process at the anterior pole. The posterior chamber is only
attached to the anterior chamber by the narrow ductus communicans and is
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice W.Wildgoose
FIG 5: Lateral view of a fancy goldfish (ranchu) with over-inflation of the anterior
chamber of the swim bladder. Despite paracentesis and antibiotic treatment
this fish deteriorated over four months and was found to have systemic gran-
ulomatous disease on post mortem examination. Bar = 1 cm
FIG 6: Radiograph of a 6 year old oscar showing mild ventral compression of the
posterior part of the swim bladder and increased radiodensity (asterisk) due
to a renal tumour. This fish did not exhibit any abnormal buoyancy. Bar = 1
cm
29 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 30
easily displaced laterally from its normal midline position or ventrally into
the body cavity by space-occupying lesions (Fig 8). The gap between the two
chambers is small, usually about one to two millimetres, but this is widened
in goldfish with enlargement of the posterior kidney with polycystic disease,
extensive granulomata or neoplasia.
Fluid in the swim bladder
There is rarely any fluid seen in the normal swim bladder, although the
epithelial cells produce a surfactant that is thought to have an anti-adhesive
and protective function. Researchers studying surfactant deficiency diseases
in humans such as premature babies have used goldfish as a model and
washed out the swim bladder (Daniels and Skinner 1994). Analysis of this
fluid shows that it contains surfactant proteins and phospholipids that bear
many similarities to those found in mammalian lungs. The radiographic
appearance of fluid in the swim bladder varies depending on the amount
present. When full of fluid, the swim bladder is barely visible and has a
homogeneous radiodensity similar to that of the surrounding tissues (Fig 11).
When partially filled, a faint area of radiolucency is seen in the centre of the
affected swim bladder chambers when radiographed in lateral recumbency:
the gas lies above the fluid and a fluid line can be detected more readily on a
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice W.Wildgoose
FIG 7: Radiograph of an 8 year old oscar with severe over-inflation of the swim blad-
der. This fish was excessively buoyant and floated on its side at the surface
for five months. The renal tumour appears as an area of increased radioden-
sity in the posterior body cavity. Bar = 1 cm
FIG 8: Dorsoventral view radiograph of a fancy goldfish (oranda) showing displace-
ment of the posterior chamber of the swim bladder to the right side due to a
polycystic kidney disease. This fish was originally presented after floating at
the surface with its right side uppermost for two weeks. Bar = 1 cm
FIG 9: Horizontal beam radiograph of a common goldfish with fluid partially filling
both chambers of the swim bladder. Excess gas is also present within the
bowel. This fish had exhibited negative buoyancy and a head-down posture
for 10 days. Bar = 1 cm
31 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 32
horizontal beam image (Fig 9). Abnormal fluid was found in 12% of goldfish
in this review and varied from clear straw-coloured fluid to white purulent
material. One of the two koi seen had a purulent fluid in the swim bladder
with granulomas and contained acid-fast bacteria.
Intestinal tympany
The similar radiodensity of bowel, liver and body fat make it difficult to
differentiate the abdominal tissues. Normally, little detail is seen within the
bowel but occasionally there may be small amounts of radio-opaque foreign
matter such as sand or grit in pond fish or radiolucent gas. Three goldfish had
excessive amounts of gas in the bowel and all these were excessively buoy-
ant (Fig 10). In one case, some gas was aspirated through the vent. All were
treated with antibiotics but showed no long-term improvement.
Rupture of the swim bladder
The absence of a thick tunica externa in the posterior chamber allows signifi-
cant volume change and in extreme cases, predisposes it to rupture. Only one
goldfish was seen with a ruptured swim bladder and this was complicated by
the presence of purulent fluid in the anterior chamber (Fig 11). This case, in
common with two orfe with ruptured posterior chambers, occurred in winter,
suggesting that low water temperatures may be a contributing factor.
Post mortem examination
Detailed post mortem examinations were performed in 35 goldfish, of which
most were submitted for histological examination. Granulomatous disease,
probably due to mycobacteria, was present in 23% of cases and all of which
were kept in aquaria. Half of these had lesions within the cranial cavity and
only a third revealed acid-fast bacteria with Ziehl-Neelsen staining. Fluid
was present in 23% of cases and bacterial culture isolated Aeromonas and
Pseudomonas spp. in the fluid, and mycobacteria in one case. It is not known
how the bacteria enter the swim bladder but this may be via the patent pneu-
matic duct or are blood-borne and enter through the vascular rete. Polycystic
kidney disease was present in 17% of goldfish. Other identifiable diseases
including ovarian disorders, renal disease and neoplasia were found in 22%
of goldfish. However, in 17% there was no visible pathology and nothing
remarkable found on histological examination. There were very few com-
mon factors and even radiography gave mixed results with an even number
exhibiting normal, over- and under-inflation of the swim bladder. This may
W.Wildgoose
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice
FIG 10: Radiograph of a common goldfish with intestinal tympany causing excessive
positive buoyancy. This fish failed to respond to paracentesis of gas and anti-
biotic therapy or diet change. The fish was euthanased due to lack of recov-
ery after eight months. The anterior bowel was grossly dilated with gas but
the swim bladder was normal. No specific cause was identified. There was
also a marked degree of spinal lordosis. Bar = 1 cm
FIG 11: Radiograph of a common goldfish with rupture of the posterior chamber of
the swim bladder and free gas in the retroperitoneal space (asterisk). The
anterior chamber (arrowed) is full of fluid and has a homogeneous radioden-
sity. This fish was presented four days after it developed a head-down pos-
ture with its tail above the water surface. Bar = 1 cm
33 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 34
suggest that small but significant lesions were overlooked elsewhere such as
in the brain.
In the other species, two of the three orfe had a ruptured swim bladder, one
of which had a granulomatous disease caused by a septate fungal infection
and the other a non-specific acute inflammation of the swim bladder. The
other orfe had a large hepatic tumour and granulomas. The two oscars had
renal tumours and over-inflated swim bladders. Of the two koi seen, one
had purulent fluid with granulomas in the swim bladder and the other a non-
specific necrosis of the posterior kidney. Two of the four tropical species
had granulomatous disease and one molly (Poecilia sphenops) revealed
pathology in the brain suggestive of a lipid storage disease.
Discussion
In goldfish, the swim bladder is a two-chambered organ located dorsally
within the body cavity, adjacent to the ventral margin of the spine. The ante-
rior chamber is lined with epithelial cells, supported by several tissue layers
and has an outer layer of dense connective tissue (tunica externa) (Morris and
Albright 1979). The anterior chamber is cuboidal in shape and has limited
capacity to change in volume. At the anterior pole, the tunica externa is firmly
attached to the Weberian ossicles and a flattened bony process at the base of
the fourth vertebra to assist in sound reception (hearing). The posterior cham-
ber is thin-walled and is thus capable of significant volume change because
it does not have a tunica externa. There is a diffuse vascular rete mirabile
system that is involved in gas secretion and absorption into the posterior
chamber, which assists in buoyancy control. The posterior chamber connects
to the left side of the proximal oesophagus by a long patent pneumatic duct
and to the anterior chamber by the ductus communicans. The total volume of
the swim bladder is about 5-10% of the total body volume. The posterior or
body kidney is a compact organ situated dorsally between the two chambers
and responsible for excretion of fluid and some nitrogenous wastes.
One of the few scientific papers on swim bladder disorders in goldfish
describes buoyancy problems affecting young short-bodied goldfish (Tanaka
and others 1998). This was given the name ‘tenpuku’ by Japanese farmers
and means ‘capsized’. Affected fish develop the problem after a marked
drop in temperature or in winter. Several different postures and positions
were identified. Many may be affected at the same time, unlike in the cases
reviewed here. The authors took radiographs and performed autopsies and
found a wide range in the size of the posterior chamber of the swim bladder
in both affected and unaffected fish. Many anatomical aspects of the swim
bladder were studied but the authors were unable to explain the pathogenesis
of the abnormal swimming and buoyancy of affected fish.
Goldfish have been subjected to short periods of weightlessness during para-
bolic flights and taken into space several times for various experiments stud-
ying the nature of motion sickness in astronauts (de Jong and others 1996,
Ohnishi and others 1998, Takabayashi 2004). In space, goldfish initially
exhibit backward somersault swimming behaviour. This gradually dimin-
ishes after several days as they adapt to the lack of gravity: the cerebellum
may be involved in this adaptation. Similar behaviour is also noted on return
to earth. Other experiments investigated the role of the labyrinth, the part of
the inner ear that is responsible for balance control. Researchers found that
following surgical removal of one or both labyrinths, fish exhibited tilting
behaviour with their dorsal surface tilting towards a light source and that the
swim bladder has a functional role as a gravity sensor (Takabayashi and oth-
ers 1993). Although these abnormal swimming behaviours were not seen in
goldfish in this review, it suggests that various parts of the brain are involved
in balance and buoyancy control.
Treatment
The response of abnormal buoyancy cases to treatment is often poor due
to the severity of the underlying disease. Euthanasia is indicated in most
instances but in the absence of obvious pathology some owners may request
treatment. In a quarter of cases seen, the owners declined euthanasia for
personal reasons or because the fish were not exhibiting signs of distress.
Many of these deteriorated within a few weeks or died at home and were
not available for further investigations. Depending on the clinical signs and
radiographic findings some of the following treatments may be of benefit in
cases where owners initially request treatment.
Environmental management
Sodium chloride salt added to the water at 2–5 grams/litre as a permanent bath
is often physiologically beneficial to freshwater fish. Increasing or decreasing
the water temperature by a few degrees, provided it is within the fish’s toler-
ance range, may alter the fish’s metabolic rate and assist recovery in some
W.WildgooseBuoyancy disorders of ornamental fish: a review of cases seen in veterinary practice
35 Fish Veterinary Journal • Number 9 • 2007
Fish Veterinary Journal • Number 9 • 2007 36
cases. Starving for 2–3 days allows the bowel to empty and eliminate any gas-
producing contents. There has been anecdotal evidence that feeding a lightly
crushed green pea (canned or cooked) once daily is thought to have a mild
purgative effect that may dislodge gas in the bowel (Lewbart 2000).
Medical therapy
In the UK, at least one proprietary pet shop medicine claims to treat swim blad-
der disorders (Aquarium Treatment 13 Swimbladder Treatment; Interpet).
However, the manufacturers have not disclosed the ingredients, making it dif-
ficult to assess which cases may benefit from these products. Antibiotics given
by immersion, injection or in the food may be effective in some cases where
bacterial infections are involved. Carbonic anhydrase inhibitors such as aceta-
zolamide have been used by injection at 6-10 mg/kg to treat gas bubble disease
in seahorses and may be beneficial in fish with over-inflated swim bladders by
reducing the production of new gas from the vascular rete.
Surgery
Fish with negative buoyancy due to an under-inflated swim bladder have had
various flotation devices fitted including cork, polystyrene and Floy® tags
with limited success (Lewbart and others 2005). Fish with an over-inflated
swim bladder can have some gas removed by paracentesis using a needle and
syringe to adjust their buoyancy. These often have a short-term effect and in
many cases the swim bladder becomes over-inflated again within a few days.
In some cases, repeated paracentesis may eventually resolve the problem.
There are reports of partial pneumocystectomy where part of the swim blad-
der is removed to reduce its size and hence the buoyancy of the fish (Lewbart
and others 1995, Britt and others 2002). Coelomic implants placed inside the
body cavity have been described on the Internet as a method of adding extra
ballast to fish that are excessively buoyant. However, other than paracente-
sis, most surgical interventions require an advanced surgical approach and
success often depends on the underlying cause.
Conclusion
Many cases in this review had no consistent clinical features that related to
the pathology found and the abnormal buoyancy may simply be a terminal
clinical sign. Many had chronic diseases despite the sudden onset and many
had granulomatous disease, probably due to mycobacterial infection. Most
goldfish with polycystic kidneys were pond fish, and most fluid-filled swim
bladders had bacteria present. All the fish in this review were from private
owners and had been kept for several years. These may differ from young
fish with similar buoyancy disorders that are culled by farmers and retailers,
and which may have other underlying causes such as genetic or congenital
defects as suggested in the hobby literature. It is clear that more detailed
research is required to improve our understanding of this common disorder.
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the American Veterinary Medical Association 213, 353–354
Wildgoose WH (2004) Malta histopathology workshop: fish neopla-
sia. Proceedings of 11th International Conference of the European
Association of Fish Pathologists, on CD-Rom
William Wildgoose graduated from Glasgow Veterinary School in 1977 and
has worked in small animal practice in London since then. He has a spe-
cial interest in exotic pets and ornamental fish in particular, and obtained
his RCVS Certificate in Fish Health and Production in 1997. He was a
contributor and the editor of the second edition of the BSAVA Manual of
Ornamental Fish in 2001.
Skin Diseases of Exotic Pets
Edited by Sue Patterson
Blackwell Publishing Ltd
Publishing Date 3rd May 2006
ISBN: 0632059699
334 pp
Paperback
Price: £37.50/US$74.99
Available from: www.blackwellpublishing.com
This is not a dermatological tome but the sort of text book you keep round
the corner from the consultation room to unobtrusively confirm you have the
correct treatment or used the appropriate scientific terminology. It is such a
pleasant book to read that I found myself flicking through a chapter or two
during coffee breaks. Each chapter is short, concise and informative. All the
common exotic pets are covered.
The book is laid out in four sections by class; birds, reptiles, fish and mam-
mals with the section on mammals unsurprisingly occupying around half
the pages. These sections are then divided by family or genus. Each section
starts with a chapter on the normal skin of the class, followed by a chapter
on examination and diagnostic techniques with a third chapter discussing the
individual skin diseases and treatments used in each family or genus. The
layout of the book is clear and logical with only one minor quibble which is
that it might have been better to arrange each disease in alphabetical order
rather than the apparently haphazard way they are listed although the index
appears thorough. The vast majority of the chapters provide a list of refer-
ences for those who wish to delve deeper in to the subject.
The section on birds provides three chapters on skin disease and treatment
with chapters devoted to caged birds, raptors and waterfowl respectively.
The next section on reptiles provides chapters on snakes, lizards and chelo-
nia. The next section is on fish which is discussed below. The fourth section
on mammals provides chapters on the skin diseases of chinchillas, ferrets,
gerbils, guinea pigs, hamsters, hedgehogs, mice, rabbits and rats. It is per-
haps a surprise to see hedgehogs as an “exotic pet” but they are occasional
patients at veterinary practices.
For the aquatic vet there is an excellent section on fish skin written by
Willie Wildgoose which finishes with a formulary of the treatments used in
Buoyancy disorders of ornamental fish: a review of cases seen in veterinary practice
This paper is based on a presentation given at the autumn meeting of the
Fish Veterinary Society in Glasgow on 17 May 2006. It was submitted for
publication on 26 June 2006.
BOOK REVIEW Fish Veterinary Journal (2007) (9) 38–40
... Swim bladder disorders and consequent buoyancy problems are encountered in ornamental fish species, especially goldfish (Carassius auratus) [9]. In the literature, there are very few publications describing this pathology [9,10]; on the other hand, swim bladder disorders are being increasingly observed according to breeders/importers and are tentatively managed in veterinary clinical practice. ...
... Swim bladder disorders and consequent buoyancy problems are encountered in ornamental fish species, especially goldfish (Carassius auratus) [9]. In the literature, there are very few publications describing this pathology [9,10]; on the other hand, swim bladder disorders are being increasingly observed according to breeders/importers and are tentatively managed in veterinary clinical practice. Several etiologies have been proposed as the cause of this condition, including poor water quality, infectious agents, poor nutrition, neoplasia, injuries, and genetic factors [9,10]. ...
... In the literature, there are very few publications describing this pathology [9,10]; on the other hand, swim bladder disorders are being increasingly observed according to breeders/importers and are tentatively managed in veterinary clinical practice. Several etiologies have been proposed as the cause of this condition, including poor water quality, infectious agents, poor nutrition, neoplasia, injuries, and genetic factors [9,10]. Disorders of the swim bladder include abnormal fluid accumulation, collapse, overinflation, and herniation. ...
Article
Full-text available
Swim bladder disorders and consequent buoyancy problems are encountered in ornamental fish, including koi carp. Nevertheless, beyond clinical and pharmacological management, they are largely underdiagnosed. In this study, nine koi carp showing abdominal swelling and abnormal swimming behavior were investigated. Clinical approach, varying from case to case, included ultrasonographic and X-ray investigations, bacteriological analysis of the collected fluid, antimicrobial susceptibility pattern, and possibly histological analysis. Diagnostic imaging, corroborating gross examination, documented swim bladder deformation/dislocation and serous fluid within the swim bladder chambers of most animals. Bacteria belonging to the Aeromonas hydrophila/caviae group and Shewanella xiamenensis were identified. S. xiamenensis strains showed a sensibility to all tested molecules except for one strain, which was resistant to tetracycline and cyprofloxacin. Antibiotic treatment succeeded in the full recovery of three cases in which S. xiamemensis infection was detected. Chronic aerocystitis was histologically documented where tissue was available. The swim bladder histopathological findings highlighted a chronic process that had compromised the quality of life of the animals. A multidisciplinary clinical–pathological and microbiological approach is highly suggested to recognize swim bladder conditions as early as possible, aiming to drive medical intervention and raising the chances of fish survival.
... Usually, clinically assessed buoyancy disorders are seen in sea turtles and aquarium fish. Such disorders are diagnosed when animals are either floating on the surface or lying on the bottom of the water (Wildgoose 2007). They generally respond poorly to treatment, and treatment methods remain a subject of investigation (Wildgoose 2007). ...
... Such disorders are diagnosed when animals are either floating on the surface or lying on the bottom of the water (Wildgoose 2007). They generally respond poorly to treatment, and treatment methods remain a subject of investigation (Wildgoose 2007). ...
... In sea turtles, buoyancy disorders can be caused by pneumocoelom derived from gas production caused by lung damage, infections in the body cavity, intestinal impaction, and (Wyneken et al. 2006). There are reports that in ornamental fish buoyancy disorders can be caused by systemic granulomatous disease, abnormal fluid in the swim bladder, polycystic kidney disease, a ruptured swim bladder, and renal tumors (Gumpenberger et al. 2004, Wildgoose 2007. The results of the 3 cases in the current report suggest that one of the causes of buoyancy disorders in Ambystoma mexicanum is pneumocoelom caused by lung perforation derived from lung lesions. ...
Article
Full-text available
As far as we are aware, there are no previous reports on the pathologic conditions of buoyancy disorders in Ambystoma mexicanum. Herein, we describe various clinical test results, clinical outcomes, and the pathological findings of an experimental pneumonectomy procedure in 3 A. mexicanum exhibiting abnormal buoyancy. The 3 pet A. mexicanum were adults, and their respective ages and body weights were 1, 5, and 6 yr and 48, 55, and 56 g. Two of these cases were confirmed via radiographic examination to have free air within the body cavity, and all 3 cases were found via ultrasonography to have an acoustic shadow within the body cavity and were diagnosed with pneumocoelom. Lung perforations were detected macroscopically in 2 of the cases, and all 3 cases had fibrosis in the caudal ends of the lungs. Removal of the lung lesions eliminated the abnormal buoyancy in all 3 cases. We concluded that air had leaked into the body cavity from the lungs, and we propose that lung lesions are an important cause of buoyancy disorders in A. mexicanum.
... inflammatory process or neurotoxins). 5,11 An increase of the volume of buoyant gas in a fish can be caused by a sudden decrease in pressure, supersaturation, occlusion of the pneumatic duct in physotomous species, traumatic or iatrogenic gas injection, and gas production by microorganisms. 8,9 In contrast, a decrease in the volume of gas in the swim bladder is most commonly associated with pneumocystitis and fluid accumulation 8 although compression by space occupying lesions such as neoplasia (i.e. ...
... Increased and decreased buoyancy can share the same etiologic processes, when they affect the pneumatic duct and the swim bladder, respectively. The reported causes of buoyancy disorders include bacterial (Aeromonas spp., Pseudomonas spp., Mycobacterium spp.), 11,13,14 or fungal pneumocystitis, 15 parasitic infestation, 16 neoplasia, chronic inflammation of the pneumatic duct, 11 epithelial metaplasia secondary to nutritional disorder, 17 congenital defect and trauma 18 . ...
... Globoid fancy goldfish, similar to the one described in this case, are also thought to develop buoyancy problems more frequently, although results of published retrospective studies do not support this hypothesis. 11 Sex and age do not appear to be risk factors for buoyancy disorders in goldfish. 5 Diet may be linked with Tempuku disease 7 while overfeeding has been associated with buoyancy disorders in Japanese koi. ...
... tetra, Moenkhausia pittieri Eigenmann (Stolk 1956a,b) and goldfish, Carassius auratus (L.) (Stolk 1956a,b;Munkittrick, Moccia & Leatherland 1985;Gill 1994;Wildgoose 2007). This is the first report of cystic lesions in kidney of flower horn fish. ...
... Unlike the present study, H. carassiirelated cyst walls were composed of a proliferating, cylindrical epithelium and a basement membrane, and in some parts, cysts were also bordered by several layers of connective tissue (Molnar et al. 1989), and cysts in copper-exposed mussels were composed of two cell layers that were proliferative (Sunila 1989). Radiogeraphs showed displacement of the posterior chamber of the swim bladder due to a polycystic kidney disease in goldfish, C. auratus (Wildgoose 2007). Radiology and ultrasonography were helpful in diagnosis of polycystic liver in flower horn fish (Rahmati-holasoo et al. 2014). ...
... Radiology and ultrasonography were helpful in diagnosis of polycystic liver in flower horn fish (Rahmati-holasoo et al. 2014). Our radiological and ultrasonographical findings support that radiology and ultrasonography can be suggested as non-invasive methods for diagnosis of cystic lesions in internal organs of fish (Rahmati-holasoo et al. 2014) and identifying polycystic kidneys (Wildgoose 2007). In this study, the relationship between polycystic lesions in kidney and oedema in urinary bladder was unclear. ...
... Diseased fish samples from different fish farms were transported to the department of Zoology and Aquaculture, Chaudhary Charan Singh Haryana Agricultural University, Hisar (India). The clinical symptoms of the diseased fish were recorded and compared to those enlisted by Sahoo and Mukherjee [22], Sudheesh et al. [23], Goni et al. [20], Lilley et al., [24], Muthu [25], Silbernagel et al., [26], Andrades, et al., [27], Srivastava [28], Shahjahan`et al., [12], Wakida-Kusunoki and del Ángel [29], Wildgoose [30], Duc et al., [17], Schwebel et al., [31], Rani and Singh [32], Durborow et al., [33]. To better understand fish health care practices in fish farms, we also examined the mortality rate and treatment and disease control practices selected by the farmers. ...
... The present study shows the clinical symptoms of diseased H. Fossilis collected from distinct fish farms such as red patches, accumulation of fluid in abdomen, cannibalism, stress, body injury, red spots, hanging symptoms in water during maximum hours of throughout the day, wounds, skin rashes, creepy curved backbone, spinal malformation, ulcers along with cotton like fungal hyphae growth and haemorrhages on body, dorsal and lateral skin lesions, fins appear ragged and split and loss of appetite. The external symptoms of diseased fish were similar to those reported by [12,17,[25][26][27][28][29][30][31][32][33]. Diseases were identified mainly on the basis of history and morphological symptoms of fish. ...
Experiment Findings
Full-text available
Heteropneustes fossilis were collected at monthly intervals from different fish farms in Haryana to monitor the incidence of any disease in cultured fish. At each fish farm 25 fish samples were collected through nets; each sample contained 40-50 fish and the percentage of diseased fish was determined. Red patches were the most prevalent symptoms of the disease reported, followed by fluid accumulation in the abdomen, creepy curved backbone, spinal deformities, hanging symptoms in water, ragging and splitting of fins. Other conditions, such as ulcers along with cotton like fungal hyphae growth, haemorrhages on body, and injury were also reported but with a lower frequency. Symptoms revealed that disease is the leading cause of mass mortality in various fish farms. Disease control and treatment methods have also been studied. This study emphasized health management issues associated with H. fossilis farming. Thus, the findings of present investigation can be appropriately employed as valuable information on diseases and health management.
... The swim bladder is important in maintaining neutral buoyancy. Abnormal buoyancy is a common presentation of ornamental fish (Wildgoose 2007a) with a number of etiologies that can be diagnosed using radiography or other imaging techniques. Positive buoyancy may be due to overinflating of the swim bladder ( Figure 5.17), torsion (rare), or gas in the coelomic cavity or other coelomic organs. ...
Chapter
Fish surgery has challenges associated with the aquatic environment such as keeping the patient moist during the procedure and operating a water‐recirculating anesthesia system. Despite the use of analogous surgical techniques and surgical instruments to those employed in mammals, fish are a very diverse taxon and specific anatomy and physiology should be reviewed before surgical procedures are performed. Surgical planning often requires advanced diagnostics such as imaging and ultrasonography. Perioperative and postoperative antinociception is recommended, although response to pharmacological agents and treatment regimens differs among species and can change according to prevailing environmental conditions. Common surgical procedures include cutaneous and intracoelomic mass excision, ophthalmic procedures, reproductive surgery, gastrointestinal foreign body removal, biopsy (including visceral organs), and buoyancy concerns.
... Reduced levels of activity, listlessness, a reduction of feeding behavior, or unusual levels of hiding are all signs that can indicate a problem such as poor water quality. A loss of buoyancy is indicative of swim bladder or diet-related issues or a variety of causes (Wildgoose 2007). Fish gulping at the surface may be normal feeding behaviour or a sign of poor water quality. ...
Chapter
Full-text available
Goldfish are members of the cyprinid family. Goldfish were originally kept in China at least 2000 years ago, where they were primarily raised as food fish. Goldfish are generalist omnivores and eat a range of food varieties, from insects to plants. All goldfish need adequate space for shoaling, keeping adequate distances between individuals, maintaining adequate water quality, and allowing all goldfish to reach their full size potential. Goldfish are motivated to shoal and may form schools in large ponds. Goldfish can be affected by a variety of health problems, including bacterial infections, fungus outbreaks, and parasitic infestations. The most efficient method of euthanasia should involve two stages, the first to cause unconsciousness and the second to ensure death. Reduced levels of activity, listlessness, a reduction of feeding behavior, or unusual levels of hiding are all signs that can indicate a problem such as poor water quality.
Article
Full-text available
A Ryukin goldfish was evaluated because of a 6-month history of progressive abdominal distention and positive buoyancy. Overinflation of the swim bladder was diagnosed, and the fish was anesthetized with tricaine methanesulfonate. Archimedes' principle was used to determine the volume of swim bladder that was removed surgically. The caudal swim bladder was exteriorized through an abdominal incision and 2 surgical clips were placed across it to limit its size. After surgery, the fish remained in a state of negative buoyancy in sternal and lateral recumbency on the bottom of the tank. Sutures were removed 15 days after surgery, but the fish died 24 days after surgery. A full necropsy could not be performed because of autolysis of the tissues, but the surgical clips and the swim bladder appeared unremarkable. Pneumocystoplasty may be a viable treatment for this condition.
Article
Goldfish (Carassius auratus: Cyprinidae) have a two-chambered swim bladder. The anterior chamber is thick walled, undergoes small volume changes, does not empty itself of gas, and assists in hearing. The posterior chamber is thin walled, undergoes extensive volume change that often results in bladder collapse, and controls animal buoyancy. Both chambers possess relatively thick inner lipid linings that differ in composition. The anterior-chamber lipids are rich in cholesterol and phospholipids, particularly in disaturated phospholipids. Posterior-chamber lipids are exceptionally rich in cholesterol but not in saturated phospholipid. Lipids from both chambers lower surface tension below that of water but are not more surface active than a cell membrane preparation. This study demonstrates a new technique for determining the role of the lipids in bladder inflation and compliance. The pressure required to initiate the inflation of a collapsed bladder (termed "opening pressure") increased after lipids were removed from the posterior chamber but not after they were removed from the anterior chamber. Posterior-chamber lipids act as an antiglue for collapsed bladders by preventing the folded inner surfaces from adhering. Anterior-chamber lipids did not act as an antiglue, and their function remains unknown.
Article
A pet Midas cichlid with a 2-year history of a distended abdomen and inadequate buoyancy control was found, radiographically, to have an abnormally large swim bladder. A recirculating anesthesic machine was constructed, and the fish was anesthetized with tricaine methanesulfonate prior to removing a portion of the swim bladder. The entire procedure lasted 71 minutes. Buoyancy problems in pet fishes are common. Causes include subcutaneous air accumulation, infectious disease of the swim bladder inner ear disease, and gastroenteritis. Reduction of the volume of the swim bladder improved this fish's ability to maintain a normal posture in the aquarium.
Article
Birds and fish show tumbling and spinning movements when subjected to short periods of weightlessness during parabolic flight. The reason for this behavior is not clear. The semicircular canal system is a rotation-detecting device; however, it seems that linear accelerations have an influence, too. Microgravity induces rotatory sensations which leads to a compensatory behavior (e.g., rotatory movements). The swimming behavior of goldfish was studied with the fish in four different conditions: normal fish (group I); fish with one eye recently removed (group II); fish with both eyes recently removed (group III); and fish with both eyes removed 10 months previously (group IV). Further, a group of naturally blind (e.g., not surgically treated) cavefish (group V) were involved in the study also. All procedures conformed to the guiding principles as required in the Dutch Law on Care and Use of Animals. Three main different patterns of abnormal swimming behavior could be observed: tumbling (pitch), corkscrew movements (pitch and roll), and spinning movements (roll). NF did not shown any special swimming pattern. One-eyed fish (group II): mostly corkscrew movements (62%). Blind fish (group III): a mixture of the three movements (17, 22 and 25%). Blind fish (group IV): mostly spinning movements (20%). Cavefish (group V): tumbling (21%), corkscrew movements (12%) and spinning movements (58%). Vision is the dominant cue, explaining the behavior of normal goldfish. When vision is absent, the fish relies on vestibular information with respect to orientation. The swimming behavior is presumably caused by an attempt to compensate rotatory illusions. As all movements were shown in the planes of the vertical canals, we conclude that these canals play a dominant role when fish are deprived from proper otolith information.
Article
This case report describes the radiographic, ultrasonographic and computed tomographic (CT) examination of an abdominal swelling in a Red Oscar (Astronotus ocellatus Cuvier, 1829). While radiography only demonstrated caudoventral compression of the swimbladder, ultrasonography found a huge tumor-like parenchyma in the caudal abdomen. CT studies detected a possible connection between the tumor and the kidneys. Necropsy and pathohistology were performed. A papillary-cystic adenoma of the kidney was diagnosed.
The Interpet Manual of Fish Health
  • C Andrews
  • A Exell
  • N Carrington
Andrews C, Exell A and Carrington N (2002) The Interpet Manual of Fish Health (2nd edn). Interpet Publishing Ltd, Dorking
Clinical and pathological investigation of "submarine syndrome" in a group of Japanese koi (Cyprinus carpio)
  • K R Hobbie
  • G A Lewbart
  • L A Mohammadian
  • K Linder
  • S Frasca
Hobbie KR, Lewbart GA, Mohammadian LA, Linder K & Frasca S (2002) Clinical and pathological investigation of "submarine syndrome" in a group of Japanese koi (Cyprinus carpio). Conference proceedings of the International Association for Aquatic Animal Medicine pp31-32
Green peas for buoyancy disorders
  • G A Lewbart
Lewbart GA (2000) Green peas for buoyancy disorders. Exotic DVM 2 (2), 7
Development of a minimally invasive technique to stabilise buoyancy-challenged goldfish Carassius auratus
  • G A Lewbart
  • L S Christian
  • D Dombrowski
Lewbart GA, Christian LS & Dombrowski D (2005) Development of a minimally invasive technique to stabilise buoyancy-challenged goldfish Carassius auratus. Conference proceedings of the International Association for Aquatic Animal Medicine pp129-130