Gas bubble disease is an environmental condition that affects fish when the total dissolved gas pressure in their water increases, causing gas bubbles to form in their circulatory systems and tissues. It occurs when water becomes supersaturated, holding more gases like nitrogen and oxygen than normal. Bubbles form internally and externally on fish exposed to supersaturated water. Clinical signs include bubbles under the skin, in fins and eyes, causing swelling and impaired vision. Diagnosis involves examining fish for gas emboli. Prevention focuses on avoiding supersaturation by managing factors that influence gas levels like temperature, aeration and algal growth. Treatment requires removing the excess gas from the water source.

1. An Assignment
0n
‘’Gas Bubble Disease ''
Course Title: Fish and Shell Fish Disease .
Course code: AAHM-351
Department of Aquatic Animal Health Management
Faculty of Fisheries, Aquaculture and Marine Science.
Sher-e-Bangla Agricultural University.
Submitted to:
Zubyda Mushtari Nadia
Lecturer at
Sher-e-Bangla Agricultural University
Department of Aquatic Animal Health Management.
Submitted by:
Mohammad Rashidul Islam
Reg: 18-08912
Level : 3, Semester : ll
Submission Date: 07.05.2021

2. Gas Bubble Disease
Introduction :
Gas bubble disease (GBD) is environmental caused trauma. In 1670, gas embolism have been
recognized a problem of fishes. In 1866, first describe the term ‘supersaturation', as an excess of
any gas in solution. Gas bubble infection previously clarified by Gorham in 1901 as comprising
of vesicle of gas attacking every one of the shallow pieces of fish body particularly fins, eyeballs
and connective tissue of the orbits so that eyes were forced from their socket, less commonly
bubble created beneath the lining of the mouth.” Gorham was the first researcher to the gas bubble
problem to a decrease in partial pressures rather than to a pathogen. Gas bubble disease was first
observed in aquatic animals and recognized in fishes held in seawater in a public aquarium. The
signs of the problems were recognized as well as the likelihood of mortality if excess air remained
in the bloodstream. Nitrogen excess was considered more important than oxygen excess in causing
the disease.
Fig: Gas Bubble Disease
So, gas bubble disease refers collection of gases in a fish's circulatory system. This may happen
when its aquarium or pond water is overabundance with gases.
Gas bubble disease is a non infectious disease. When the total dissolved gas pressure increases, it
creates primary lesions in the blood and tissue. Gas bubble disease is the opposite types problems
of hypoxia. It may occur in a chronic form at about 103% and in an acute form at above 110-115%
total gas pressure (TGP). In chronic form, fish specially fry will die slowly without presenting
symptoms.

3. Most gas emboli are delivered by overabundance nitrogen since oxygen is acclimatized
metabolically and along these lines more averse to shape determined air pockets. At the point when
fish inhale supersaturated water, the overabundance gas can frame emboli in different tissues. The
seriousness of the illness relies upon the quantity of gas bubbles shaped and the tissues influenced.
During the photosynthesis watercontaining heavy aquatic plant growth may be saturated with
oxygen and may become supersaturated upon warming. Artificially supersaturated water occurs
in plunge pools from dams, when water is heated such as power plant effluent and if air is entrained
into pipes or pumps where pump pressure forces gas into water solution.
Causes and Pathogenesis :
In different temperature, salinity and pressure, water holds different amount of gases. If the
concentration level of gas in water is same of that the water can hold for its pressure, temperature
and salinity, it is called ‘saturated'. When there is more gas in water than it can hold, it is called
‘supersaturated ‘. And when the concentration level of gas is less than the water can hold then it
is called ‘undersaturated'.
Then main gases found in water are Oxygen, Carbon dioxide and Nitrogen. Supersaturated water
attempt to release the excess gases in bubble form. At the point when a fish is presented to a
supersaturated water environment, the gas broke down in the tissues and liquids is compelled to
emerge from arrangement and if this happen too quickly, bubbles structure in various pieces of the
fish, causing various signs and symptoms.
• Pressure can raise the amount of gas per unit volume that the water contains. One of the
best practical example of this law is offered by opening a bottle of carbonated beverage.
When the cap is eliminated from the bottle, gas is heard getting away and bubbles can be
seen forming within the drink. This is the carbon dioxide gas emerging from the solution
as a result of sudden exposure to lower atmospheric pressure.
• A quickly changing atmospheric pressure over the path of hurricane Andrew in 1992 has
prompted GBD which was considered a major culprit in the death of just about 10 million
marine fishes valued at $7.8 million.
• The more profound the water, the more gas the water can hold.

4. • Water that is pumped through pressurized framework will hold more gas than
unpressurized framework.
• Normally more temperate water contain less gas per unit of volume. Thus, if the
temperature of cold water with a normal dissolved gas content is enhanced because of
increased environmental temperature, supersaturation conditions can be formed.
• Problems with GBD are commonly encountered when fish are cultured in the heated
effluents of power plants or where heat is recaptured from steam creating facilities.
• The higher the saltiness, the less gas water can hold. This is because the dissolved salts
take up room that the gas could be utilizing.
• Supersaturated conditions can also result if a gas for example nitrogen is forced into water
solution-
a. A crack in a pipeline
b. Water falls
c. Excessive splashing
Host Species
The disease may affect any kind of fish or invertebrate anyplace when in supersaturated waters.
The mortality and pathological changes vary with age and the species of fishes caused by
supersaturation.
Fish fry become very susceptible post-hatch when they start swimming up for food (at about 16
days). Steelhead trout fish are most sensitive (average thresh old of 102-103% TDG before chronic
problems develop) whereas coho salmon are least sensitive (average threshold about 115.7%
TDG).
Clinical Sign and Symptom
The gas bubble disease can be recognized by the development of little gas rises under the epidermis
that includes the formation of gas bubbles in the skin, the gills and eyeballs causing exophtalmia.
Gas bubbles may also form in fins, in the vascular system where they regularly cause embolism

5. and in the mouth opening. The Gas Bubble Disease may cause floating problems because of the
unreasonable measure of gas in their bodies, ultimately leading to upside down swimming and
death.
Fig: Gas Bubble Diseased Fish
Acute gas bubble disease shows as intense mortality and may happen in minutes. Eggs float to the
surface and fish may show out of hyperinflation of their swim bladder, cranial
swelling, exophthalmos, visual impairment, swollen gill lamellae, pneumoperitoneum or gas
bubbles in the yolk sac. About 100% of fish may die.
Chronic gas bubble disease results in a slower mortalities of fish, hyperinflation of the swim
bladder, emboli in the gastrointestinal tract and mouth, and secondary infections can prompt
higher death rates.
Gas bubbles are macroscopically apparent inside the cornea of the eye. Bubbles inside the skin may
be visible as an external protuberance or felt by moving a hand along the fish. Internal bubbles are
not apparent and may cause tissue degeneration. It is exceptionally uncommon to have just internal
bubbles without external bubbles.
So eventually these manifestations found in the diseased fishes:
• Bubbles can form in the body cavities of fish, such as beneath the eyes that causing
exophthalmia, or between the layers of skin tissue.
• Gas bubbles can form in the sleazy tissue between the fins on and along the back and tail.

6. • Tiny bubbles can form inside the circulatory system, blocking the flow of blood and
causing death of the tissue.
• More harmful bubbles can form in the gill lamellae and clog the blood flow, occasionally
resulting in death by suffocation.
• Vesicle are clearly visible beneath the skin, specifically in the head area, in and around the
eyes.
• The diseased fish will make a croaking sound when taken out from the water and the skin
will crackle if we run our finger across it.
Diagnosis
Supersaturation disease can be hard to
affirm since issues noticeable to the unaided
eye (gross lesions) are usually not present
when the fish are found. Gill biopsies and
wet mount assessment of different organs
under the microscope may show gas emboli
inside the circulatory system.
Supersaturation is hard to determine to have
a water test kit since most kits don't measure
dissolved nitrogen. Fig: Gas Bubble Disease in Fish Body
Most cases of gas bubble disease can be analyzed upon a physical test. This disease may develop in
three different stages:
• Pressure unequilibrium resulting in overabundance gas formation.
• Metabolic and functional system diminishes.
• Complete system dysfunction (death).
Diagnosis is made by the observation of general clinical signs and lesions. The presence of gas
emboli in vessels of the gills, fin rays, and eyes are symptomic. The clinical signs are helpful but
fish may die suddenly without apparent cause.

7. The presence of gas emboli is characteristic. Bubbles may be pressed from a fin or gill clip while
it is held submerged. By using a ‘saturometer’ the total concentration of dissolved gas in the water
source should be measured. Post-mortem findings Include interior gaseous accumulation in the
swim bladder and visceral peritoneum. Histology may uncover oedema of the secondary lamellae
of the gills and impediment of the large branchial vessels.
Prevention
For effectively prevent gas bubble disease, it is very important to evaluate all the potential reasons
and eliminate them from the framework. It is clearly better to avoid a situation than to have to cure
one.
• Keep away from the causes of supersaturation, if possible.
• Change the water to restore the proper gas balance. Little gas bubbles in fish can be
prevented and fairly restored by relocating fish into deep water area that contains higher
pressures and higher amount of gases can be dissolved in the water. This will cause nitrogen
overabundance to be dissolved into the body tissues and the gas bubbles will gradually
vanish.
• Clean away algae and dimish the volume of live plants.
• Decrease lighting to decrease oxygen production by the plants.
• Good aeration is one of the easiest approach to control GBD. Bouncing, splashing, spraying
as well as cascade culture water through air before it arrives at fish will promote the release
of supersaturated gases.
• Increase saltiness, if conceivable.
Treatment
The main treatment of gas bubble disease is to determine the cause of the microbubbles inside the
framework. Any breaks or issues with the framework ought to be managed immediately.Treatment
of the disease involves wiping out the excess gas in the water source.
This could include circulating air through the water source to permit it to equilibrate with air.
A packed column degasser can be utilized to strip the excess gas from the water. Fish that

8. recuperate from an outbreak have a variable prognosis depending on the degree and the span of
supersaturation they encountered.
Transmission
Due to the environmental nature of this disease, transmission between fish does not occur.
Human Health Significance
There are no human health concerns associated with GBD(Gas Bubble Disease) in fish.
Conclusion
Gas bubble infection is related with the supersaturation, with nitrogen or oxygen, of the water
wherein fish are kept. It happens when the absolute pressing factor of gases dissolved in water is
higher than the encompassing atmospheric pressure. In aquariums, causes include leaks in pumps
or valve frameworks that can suck air under pressure or unexpected temperature inclinations. Fish
transported via air may likewise create gas bubble problem.
Excessive algal blooms have additionally been accused, by creating more oxygen than can diffuse
into the water which supersaturates the lake. Most gas emboli are delivered by excessive nitrogen
since oxygen is absorbed metabolically and accordingly more averse to form persistent bubbles.
However, extremely high oxygen levels are perilous.
At the point when fish inhale supersaturated water, the overabundance gas can form emboli in
different tissues. The seriousness of the disease relies upon the quantity of gas bubbles framed and
the tissues affected. Brain damage, behavioural abnormalities and death can also occur. So we
should careful about this environmentally caused disease.

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