Diseases of Arowana
When a fish is placed in a artificial environment from its natural
habitat, the chances of the fish getting disease is high. The stress
due to the changed environment and also other stress factors like
different feeding regime from the natural habitat and bad water
quality management will also cause the fish to acquire disease.
Therefore, one should be aware that keeping the stress level low
is the best way to prevent disease rather than curing the fish after
it acquired the disease.
Generally the dragon fish have a great resistance against diseases
so long as they are not weakened by bad treatment, such as spoilt
food, polluted and contaminated water, lack of oxygen, sudden change
in water temperature, or other conditions the result of human negligence
and ignorance that will cause stress and injury to the fish. Remember
that the fish remains healthy as long as it is allowed to live in
an environment to which it has adjusted.
The List below are some of the more common diseases associated
with the dragon fish, their symptoms and suggested remedies.
1. Tilted (overturned) Gill Covers
Fouled water as a result of rotting food particles and excretions.
The strong presence of NH3, NO2 and NO3 can reduce the content
of oxygen in the water.
Space constraint - When the Dragon Fish is growing, it not only
needs nutrition, it also needs a lot of room to move about. Otherwise,
the gill covers may be affected. They may tilt over.
Change in temperature - The temperature of the water in the
aquarium should always be maintained. The sensitive gills can
be affected when it is either too hot or too cold suddenly.
At the initial stage, the movement of the gill covers is not regular
and breathing is also faster and abnormal. Next, the gill covers
may become concave and the edge may curl upwards, causing the gills
to be exposed in the water.
Finally, at the serious stage, the fish pushes its head up constantly
to the surface for air while at the same time loses its appetite.
This means the internal gills have become damaged and probably infected
with bacteria, affecting the function of breathing and this can
lead to death eventually.
When it is first discovered that the Dragon Fish is not breathing
properly, the water should be changed immediately. Every 2 to 3
days, 20% of the water in the aquarium should be changed. Air pump
should be further activated and air bubble stones could be added
so that oxygen level in the aquarium could be increased. Also, change
the filter media to coral sand.
When the edge of the gill cover is slightly curled but not yet
hardened, other than changing water, and increasing air/oxygen supply,
strong water current could be created. There may be 50% chance of
a cure without the need to operate.
When the gill cover is tilted and hardened exposing the gills,
the only way left is to trim off the tissues of the tilted region.
Tools needed are scissors, surgical spirit, gloves, plastic bag
and a rubber sheet. Also water-proof fine sand paper to polish clean
the gill cover affected by cut tissues. The above tools must be
When all equipment have been properly treated, the Dragon Fish
should be transferred to a smaller fish-tank leaving the original
tank to be filtered and pumped with air to increase oxygen content.
With 1/3 of water in the small tank, anesthesia should be administered
within the plastic bag which contains the sick Dragon Fish. It must
be established prior to the operation that the Dragon Fish has completely
lost consciousness before it can be removed (take care not to cause
dehydration). Then use a clean pair of scissors to trim the edge
of the gill covers.
After cutting, it is necessary to apply antiseptic medications
to the trimmed edges. The Dragon Fish should be promptly put back
into its own aquarium to await its regaining of consciousness. More
antiseptic medication may be added to prevent wound from being infected
When it regains consciousness, switch off all lights and allow
the Dragon Fish to recuperate. Feeding can be stopped if it has
no appetite. Additional equipment may be fitted to create waves
in the aquarium. The cut portion must grow again before the operation
is considered successful.
2. Cloudy Eyes
This can be caused by:
- Eye-injury as a result of bad handling
- Contaminated water
Initially, one eye may appear cloudy. It then becomes moldy as
though a membrane is hanging over it. Eventually, the eyes may swell
and are covered with blueish white foreign matter. At this stage,
if they are not treated may result in death or blindness.
At the initial stage 1/3 of water should be changed and coarse
salt should be added.
Water temperature should also be increased to 30°C to 33°C.
Observe for 2 days. If condition improves, water should be changed
every third day (1/4 of water) and more salt may be added until
complete recovery. At the intermediate stage, medications may be
needed to bathe the fish in. Such medications will have their own
instructions to be adhere to on application. When eyes become moldy,
recovery may take 3 to 5 months. If swelling subsides, medication
may be reduced or stopped eventually. After recovery, eyes may appear
smaller but that should be normal.
3. Protruding Scales Disease
This often occurs when Dragon Fish is young. The adult Dragon Fish
seldom gets affected by this disease.
- Events causing extreme temperature changes within the aquarium.
- Contaminated water.
Initial stage - Scales tilt at every 5th to 8th scale. Blood traces
may be seen at the root of scales. If not arrested at this stage,
scales will gradually tilt, redness may appear and the scales will
not be able to protect body causing bacteria attacks to the body
of the Dragon Fish. The scales may all drop off causing the body
to decay and the fish to die.
Add coarse salt and increase temperature to 32°C to 34°C.
Increase oxygen content in the water and change water (1/4) every
3 to 4 days. Water may be heated prior to change. Add copper sulfate
medications to the water.
4. Rotting Gills Disease
Caused by a type of parasite which cannot be seen by the naked
eye. These parasites hide in the gills sucking and absorbing all
the nutrients from the Dragon Fish. The cells of these parasites
multiply speedily at 25°C. This disease is highly contagious.
Cause: Polluted water or water which has not been
changed for a long period.
Symptoms: The fish is breathing very fast and
its color is dull.
Cure: Similar to that of the "White Spots"
Disease (see section on the "White Spots"
5. Stomach Ailments
This occurs when fish is very young - mainly due to eating stale
food or it may have been injured by the sharp pincer of the prawns
causing the internal wall of the stomach to be infected with bacteria,
resulting in a swollen belly.
Initial stage - Swollen stomach with a red swollen anal region.
At the advanced stage, the Dragon Fish may be seen to have lost
its balance dipping its head downwards.
At the moment cure is limited, but commercially available fish
medications may be given and water may be changed with temperature
increased by 2°C to 3°C.
6. 'Red Spots' Disease
This is often regarded as a terminal disease and it affects mostly
Red spots occur on the lower back portion of the body. Early stage
- patches of red spots, gradually swelling occurs, scales are upturned
and finally the fish may slowly rot to death.
Try increasing temperature to 36°C plus bathing it with fish
medications available commercially.
Most of these parasites come from the live food that are used to
feed the Dragon Fish and are passed to the Dragon Fish during feeding.
the parasites that affect the Dragon Fish are mainly the fish lice
and the anchor worm.
Approximately 3 to 5 mm long, can be seen with the naked eye on
the external body. It has a flattened body shell. It has a needle-like
structure at the mouth to suck out the body fluid causing the fish
to lose its lusture, at the same time causing the fish to be uncomfortable,
scraping the side or bottom gravel of the aquarium.
Found mainly around the fins or within the body of the fish. The
head of the worm is forked and it sucks the nutrients from the fish
directly. The length is about 1 cm. The affected region is often
red and swollen with traces of blood and then decay sets in. An
affected fish may appear to be irritable, scraping and rubbing against
the sides of the aquarium and losing its appetite in the process.
The above parasites can be killed by using copper sulfate medications.
The fish lice can also be gotten rid of by keeping the Dragon Fish
in a concentrated salt solution. Oxygen content should be increased
in the aquarium during this soaking period.
Note: Once the Dragon Fish has been infected by parasites, the
tank must be sterilised.
8. 'White Spot' Disease
This disease is very common among fishes. It originates from a
type of ICH bacteria. It can multiply alarmingly fast, and can flourish
at body temperature 25°C from a single cell to 3000 over cells
in a hour. Under high temperature, it can stop multiplying and even
ICH bacteria only attack the fish with low resistance. The bacteria
suck up the body fluid of the fish. The affected region looks like
At initial stage, the disease affects mainly the fins. The fish
that has been infected with this disease tends to scratch itself
against the sides or bottom of the aquarium to rid its itch. Its
appetite deteriorates greatly and fin ends starts to rot. Lastly
when it attacks the gills, the fish may die.
The illness should be arrested at once as it is highly contagious.
- 1% salt
- 0.8 gm of Quinine in every litre of water.
- Use available commercial preparation from Aquarium shops.
Warm the water by increasing by 2°C to 3°C in temperature
and adding air-pumps to increase the oxygen level in the aquarium.
In the process of treatment, the Dragon Fish should be fed nutritious
food so as to build up its physical resistance. Upon recovery, it
is advisable to disinfect the entire aquarium.