Non-Infectious Diseases of Fish (Environmental, Nutritional & Genetic)

Non-infectious diseases of fish are a group of diseases that are not caused by an infectious agent, such as a virus, bacterium, or fungus.

Instead, these diseases are typically caused by environmental, or nutritional factors, or by the fish’s own immune system.

These illnesses are also known as communicable or transmissible diseases. This illness does not directly invade or transfer from one animal to another.

Diseases rooted in environmental manipulation, nutritional imbalances, genetics, or lifestyle choices are called infectious illnesses.

What is Non-Infectious Disease

Noncommunicable or non-communicable diseases are called such because they are chronic and are not able to be transmitted between animals.

Fish can suffer from a variety of diseases that are not caused by infection. These diseases can be caused by environmental factors, nutritional problems, or other health issues.

Non-Infectious Diseases of Fishes

Some of the most common Non-Infectious Disease of Warm water & Cold Water Fishes include;

  1. Environmental related problems: Gas bubble disease, hypoxia, anoxia, swim bladder diseases etc.
  2. Nutritional disease: Scoliosis, lordosis etc.
  3. Hereditary disease: Autoimmune disease

Environmental Diseases of Fish

Diseases occur due to interference with the water environment is named environmental diseases or failure.

Diseases triggered by harmful environmental elements or disruptive environmental factors are called environmental diseases.

Aquatic medium has direct contact with the fish’s metabolic process, where the influences of soil elements and environmental factors of water quality come into play to determine fish health.

The concentration of water close to fish is directly linked to the biochemical process they undergo in the water.

The structure and environmental factors of the water will affect water quality, which is connected to the health of fish and aquatic life.

Causes of Environmental Diseases of Fish

Inadequate Aeration & Water Exchange

Fish need dissolved oxygen in the water to breathe. If the water does not have enough dissolved oxygen, the fish will suffocate and die.

Inadequate aeration is one of the leading causes of fish diseases.

Another reason why inadequate aeration and water exchange cause fish diseases is because it allows toxins to build up in the water.

These toxins can come from fish waste, uneaten food, and chemicals that are used to clean the tank. When these toxins build up, they can make the fish sick.

Inadequate aeration and water exchange can also cause stress in fish. Stress weakens the immune system and makes fish more susceptible to diseases.

It is important to remember that even though fish may look calm, they are still animals and can get stressed easily.

Turbid Water

In recent years, water turbidity has become an increasingly pressing issue in many parts of the world.

There are a number of reasons why water may become excessively turbid, but most common reasons are the presence of soil particles or phytoplankton.

Over accumulation of both turbid particles are harmful for aquatic organisms.

Turbid water is water that is cloudy or filled with particulate matter. While turbid water does not necessarily contain pollutants, it can still cause stress to fish and lead to physical disorders.

When fish are in turbid water, they are constantly using energy to filter out the particulate matter.

This filtering process puts a lot of strain on the fish and can lead to physical disorders such as Gill damage, Fin erosion, and Eye damage.

In addition to the physical stress, turbid water also causes psychological stress to fish.

Accumulation of Black Soil

In recent years, there has been an increase in the accumulation of black soil in rivers and lakes. This is a major problem for fish, as the soil can cause disease and death.

Water Pollutant

There are several ways in which pollutants can accumulate in waterways. One way is through agricultural runoff.

When farmers use chemical fertilizers and pesticides on their crops, these chemicals can wash into rivers and lakes, where they can harm fish.

Pollutant can accumulate is through urban runoff. When rain falls on city streets, it picks up dirt, oil, and other pollutants.

This polluted water then flows into rivers and lakes, where it can harm fish.

The accumulation of pollutant (eg., insecticides and others) in waterways is a major problem for fish populations.

The soil can cause disease and death, and it can also make waterways unsuitable for fishing or swimming.

Heavy rainfall can cause a sudden decrease in salinity and an increase in turbidity of water, which can lead to a decrease in dissolved oxygen levels.

This can be harmful to fish, as it can cause them to suffocate.

This can include everything from physical changes to their bodies, to behavioral changes. In some cases, fish may even become more vulnerable.

Toxic ammonia, NO3, H2S Formation

Ammonia, Nitrate and Hydrogen Sulfide are all toxins that can cause disorders in fish. Ammonia is the most toxic of the three and can cause gill damage, organ damage and death.

Nitrate is less toxic but can still cause problems such as gill damage, respiratory distress and decreased growth.

Hydrogen sulfide is the least toxic but can still cause problems such as skin irritation and eye damage.

List of Environmental Diseases

The health of fish is a good indicator of the health of the environment they live in. Poor water quality can lead to disease in fish, which can have serious impacts on their populations.

There are many different environmental diseases of fish, and they can be caused by a variety of factors, including pollution, changes in water temperature, and changes in the food supply.

Some of the most common environmental diseases of fish include gas bubble disease, hypoxia, anoxia, acidosis, alkalosis, thermal stress etc.

These diseases can often be prevented with proper management of the environment.

Thermal Stress

Thermal stress is one of the leading environmental stressors of fish, and can have profound effects on fish physiology.

Thermal stress can impact fish in a number of ways, including by altering gill structure and function, impacting the heart and circulatory system, and affecting the kidneys and other organs.

These impacts can lead to a number of physiological changes in fish, including an increase in heart rate and respiratory rate, as well as changes in blood pressure and blood flow.

These changes can impact the ability of fish to cope with other stressors, such as predators or toxins. In some cases, thermal stress can even cause death.

Thermal stress is a major concern for fisheries managers and scientists, as it can have serious implications for the health of fish populations.

Understanding how thermal stress affects fish physiology is essential for developing effective management strategies to protect these valuable resources.

Gas Bubble Disease

A gas bubble is an air-filled space in a fish. Gas bubbles can form in different parts of the fish body, including the skin, fins, eyes, and internal organs.

Gas bubbles are usually caused by a change in water pressure, temperature, or chemical composition.

Gas Bubble Disease (GBD) is a condition that affects fish when they are exposed to sudden changes in water pressure and/or temperature.

GBD can cause the formation of gas bubbles in the fish body which can lead to death.

Symptoms of GBD include:
-Swelling of the body
-Eyes popping out of sockets
-Bubbles coming out of gills and mouth
-Loss of balance and swimming ability

If you see any of these symptoms in your fish, it is important to seek medical attention immediately.

Dissolved Oxygen Imbalance (Hypoxia & Anoxia)

Most fish cannot live in water with low levels of dissolved oxygen (hypoxia) or no dissolved oxygen (anoxia).

They need oxygen for their gills to extract oxygen from the water and for their cells to function properly.

When fish are exposed to hypoxic or anoxic conditions, they may try to find refuge in areas with higher levels of dissolved oxygen.

However, if the hypoxic or anoxic conditions persist, the fish will eventually suffocate and die.

Fish that live in waters that are frequently hypoxic or anoxic have several adaptations that allow them to survive in these conditions.

For example, some fish have a special type of hemoglobin that is more efficient at binding to oxygen.

Other fish can increase their blood flow to their gills, which allows them to extract more oxygen from the water. Some fish can also breathe air directly through their skin.

pH Imbalance (Acidosis and Alkalosis)

Acidosis and alkalosis are conditions that can occur in fish when the water around them becomes too acidic or too alkaline.

This can happen naturally, but it can also be caused by humans releasing pollutants into the environment.

Acidosis and alkalosis can cause a number of problems for fish, including difficulty breathing, reduced ability to swim, and death.

Acidosis occurs when the water around a fish becomes more acidic than usual. This can be caused by natural processes, like decomposition, or by humans releasing pollutants into the environment.

When acidosis occurs, it can cause a number of problems for fish, including difficulty breathing and reduced ability to swim. In severe cases, acidosis can even lead to death.

Alkalosis occurs when the water around a fish becomes more alkaline than usual.

Toxic disease

Toxic algal blooms that contain Karenia mikimotoi, harmful zooplankton such as Pelagia noctiluca, and other environmental threats, such as pollution, spurred severe gill diseases and injuries in salmonids such as Atlantic salmon and pink salmon.

Nutritional Diseases of Fish

There are many nutritional diseases that can affect fish. Some of the more common ones include:


This is when a fish does not get enough of the right nutrients in its diet. This can lead to problems with growth, reproduction, and immune function.

Vitamin deficiencies

If a fish does not get enough vitamins in its diet, it can lead to problems such as reduced growth, poor immune function, and even death.

Mineral deficiencies

Just like with vitamins, if a fish does not get enough minerals in its diet (such as calcium, phosphorus, and magnesium), it can lead to serious health problems.

Lipid disorders

These occur when there is an imbalance of fats in the diet of a fish. This can cause problems with growth, reproduction, and metabolism.

Hereditary or Genetic Disease of Fish

Hereditary diseases of fish are caused by genetic mutations that are passed down from parent to offspring.

These diseases can be debilitating and often fatal, making it difficult for affected fish to compete for food and mates.

Some of the most common hereditary diseases of fish include:

Neoplastic Conditions (Tumor)

Tumors in fish can be caused by different things. One way this disease can be caused is by a change, or mutation, in the DNA of the fish.

These changes can be passed down from parent to offspring.

Another way tumors in fish body can be caused is by something called “chromosomal instability.”

This means that there are changes in the number or structure of the chromosomes in the cells of the fish.

These changes can also be passed down from parent to offspring. Tumors in fish body is not a new disease.

Auto-Immune Disease

Auto-immune disease is one of the most common diseases among fish. It occurs when the body’s immune system attacks and destroys healthy cells by mistake.

This can happen for a variety of reasons, including exposure to certain chemicals or viruses. Auto-immune disease can be difficult to diagnose, as symptoms can vary greatly from fish to fish.

In some cases, the only symptom may be a loss of appetite or energy. In more severe cases, however, fish may develop open sores, fin rot, or white patches on their skin.

If you suspect that your fish may be suffering from auto-immune disease, it is important to seek veterinary care as soon as possible. With proper treatment, most fish will make a full recovery.

Body Deformities

Body Deformities disorder in fish is a condition where the fish’s body shape is abnormal.

The most common cause of this condition is genetic, but it can also be caused by environmental factors such as poor water quality or nutrition.

Body Deformities can affect the fish’s ability to swim, eat, and breathe. In severe cases, the deformities can be fatal.

There are many different types of body deformities, but some of the most common include: kinked spines, bent necks, twisted tails, and malformed fins.

Treatment for Body Deformities is typically not necessary, but if the deformity is severe or causing the fish distress, there are a few options available.

Surgery is sometimes used to correct severe deformities, but this is usually not necessary.

Swim Bladder Disease

Swim bladder disease is a problem that can affect both freshwater and saltwater fish.

It occurs when the swim bladder becomes inflamed or enlarged, which can cause the fish to struggle to stay upright and swim properly.

Swim bladder disease can be caused by a number of factors, including poor water quality, incorrect diet, or exposure to toxins.


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