A description of common aquarium fish diseases

Freshwater fish in aquarium with black backdrop

The following should only be used as a guide for the identification of potential fish diseases. If you have a problem related to fish disease in your aquarium, it is best to consult your local fish store for a diagnosis and possible treatment.

Acidosis/Akalosis Symptoms:

Fish shows an excess of mucous, the skin becomes inflamed and the gills may bleed and deteriorate. Fish may also display darting movement and may jump in an attempt to leave the water. Fish also shows signs of increased respiration and can be seen gasping for air at the water surface.

Cause:
Fluctuating pH values causes this problem. Most fish can tolerate a pH between 6.0 and 8.0. If the pH drops below 6.0 skin problems – acidosis – may develop. A pH above 8.0 on the other hand can cause the erosion of skin and gills.

Treatment:
An immediate water change is recommended. If the pH remains unchanged, check with your fish store. There are several products on the market that can either raise or lower your pH. If the pH fluctuates frequently, you should take routine measurements to assure a balance which your fish can tolerate.

Bacteriosis Pinnerum (Fin Rot) Symptoms:

Fin rot begins with a slight discoloration of the edges of the fins, making an early detection difficult. As the disease progresses, the fins begin to fray. The deterioration continues, resulting in only remains of the fins, once the disease is in it’s terminal stage.

Cause:
Several bacteria cause Fin Rot, namely “Pseudomonas Flourescens”, “Aeromonas Sp”. and “Haemophilus Piscium”.

Treatment:
Fin Rot is considered difficult to treat. It is recommended to consult with your local fish store about the correct diagnosis as well as a possible treatment.

Infectious Dropsy Symptoms:

Typical dropsy has several symptoms: bulging eyes, regressing eyes, pale gills, inflamed anus. In some cases the belly may be inflated, red spots can be seen on the skin, as well as damage to the fins.

Cause:
This disease is caused by a pathogen on which researches cannot agree. It is widely believed that 2 bacteria causes dropsy, namely “Aeromonas Punctata” and “Pseudomonas Flourescens”.

Treatment:
Like Ich, dropsy is extremely infectious. Fish are mainly receptive to dropsy if they have been weakened by stressful conditions caused by poor water conditions or another disease. Treatment is difficult, therefore prevention is key. Good maintenance of the water conditions as well as early detection and treatment of other diseases is a good measure. If a fish is diagnosed with dropsy, the ailing fish should be immediately removed and destroyed.

Gas Bubble Disease Symptoms:

Bubbles/blisters can be found beneath the skin and inside the body. They are mostly found around the head and the eyes.

Cause:
A condition known as “over saturation” is created due to the dissolving of excess amounts of gas. A certain amount of gas is always dissolved in liquid in relationship to such factors as pressure and temperature. When these gas levels are to high, the water will constantly attempt to release the gas in the form of small bubbles. Too much sun and the heavy plant and algae growth associated with this is a common cause of over saturation. Since the plants take up and release a lot of oxygen, the fishes’ blood can itself become over saturated.

Treatment:
Reduce the amount of sun light the aquarium is exposed to. Further, an air stone can help prevent problems.

Ichthyophthirius (ICH) Symptoms:

The entire body of the fish including the fins and gills are effected. White spots can be seen with the bare eye. The appearance of these spots is often compared to salt grains. Eventually the skin will get slimy and the fish will rub its body against rocks and decorations. The fish will close its fins, get thinner and less and less active.

Cause:
Ich is caused by an organism called “Ichthyophthirius multifiliis”. The life span of this parasite consists of three stages. 1. Growth – The organisms attach to the fishes’ skin. 2. Cyst – After dropping to the bottom of the tank the organisms divide while protected by a gelatin-like covering. 3. Infectious – The divided spores seek for a new host.

Treatment:
Ich is a highly infectious disease and should be treated immediately. If Ich is detected, it is best to treat the entire aquarium due to its highly infectious nature (vs. treating individual fish in a hospital tank). There are many different products and your local fish store should be able to help you with the recommendation of a medication as well as treatment instructions.

Lack of Oxygen Symptoms:

Increased respiration, open gills, lose of color, gasping for air (often at the water surface), fish appear restless.

Cause:
Excessive decaying matter such as food, dead plant matter which utilizes oxygen during the decaying process, nocturnal respiration of plants, and high water temperature at which less oxygen is dissolved in the water.

Treatment:
Aeration of the water is immediately required to avoid fish from dying from suffocation. A common misconception is that an airstone will provide adequate oxygen to the water. In reality, the best source of oxygen is provided by a good filter, which allows oxygen to be dissolved through surface turbidity during the return of the water to the tank. Further a good balance of plants will help stabilize the oxygen levels. Last but not least, all decaying plant matter, foods and algae should be removed from the aquarium.

If the problem is serious, an immediate water change should be done. Adding fresh water will significantly increase oxygen levels.

Last updated: April 14th, 2014 by algone

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