Diseases Caused by Poor Tank Conditions and Mal Nutrition – Part 2

Fish health is related to many factors. Tank conditions and nutrition are playing a significant role in fish health. In this article, there is more about the diseases caused by tank conditions and malnutrition.

Hole in the head (HITH) Disease


Image Source: https://yashwantnaik.com

Hole in the head is an aquarium disease and it can take place in both saltwater and freshwater fish. It is called head and lateral line erosion (HLLE) or hole in the head (HITH). The difference is that the disease Hole in the Head attacks mostly the freshwater fish while the other starts from the head and spreads down the sensory line that runs the flanks of saltwater fish. This is a complicated illness and can be fatal if not treated early and properly.

Like other aquarium diseases, this is also curable but the only issue is that its symptoms show at a later stage. But what makes the treatment complicated is that the cause is not easy to find out. This is because there is a combination of several factors or causes of the disease to take place and that is what makes the situation unclear for an aquarist to treat it accurately.

Image Source: http://scapeclub.org, User: Mathman

Some pathogens linked to the disease are Spironucleus, diplomonad species of Hexamita, and Octomitus but it is very difficult to determine if they are a cause of the disease or other opportunists are making the best use of the poor environmental condition of the fish living in an aquarium. Post-mortem examinations have revealed the link of both to the disease. That is why for successful treatment, do not miss out on the role of pathogens.


The fish after getting infected develops pale spots over its head which are holes. The eroding skin tissues create a hole in the spot. With time, erosions and holes may spread around the gills, eyes, and mouth area. If the infection becomes severe, strings of inner body-liquids start flowing out of the holes. The fish refuses to eat and you can notice a hollow-belly appearance on its overall body.

As the infection becomes more mature, these spots become larger and look as if another fish or bug has bitten chunks out of the fish while it’s alive.

When the infection reaches this advanced stage, the fish is in real trouble. The immune system is broadly destroyed. The open holes become easy entry points for many other pathogens to make their way to the inner body of the fish. These pathogens can also cause other kinds of diseases to the fish.


There have been several research studies on HLLE but no certain causes are considered the key reason for the disease. Activated carbon and its dust form seem the most obvious reason for the outbreak of HLLE in marine fish like tangs. Nutritional deficiencies are also strong triggers of HLLE. Vitamins and dietary iodine are highly essential for the fish and when these two essential portions fall below the normal levels, the fish will suffer.

Dropping water quality also plays a significant role in triggering the disease. If the level of nitrate (NO3) has become high in the fish tank, the fish are likely to submit to the disease faster than other fish in other tanks where the water quality is higher and water is clean.

Stray voltage is also a considerable threat to the fish. It can lead to creating suitable circumstances for HLLE.

Stressed fish are at a decreased level of immune; their defense system becomes weak against any infection. Keep an eye on your fish and whether you find the symptoms of HLLE or not. In any case, if you find some stress indications in the fish, take action immediately to eliminate the stress source or the reason. Any adverse condition is a certain cause of several health disorders in the fish and must be rectified instantly.

One of the possible reasons for the disease is the nutrient deficiency in the aquarium which the long period of use of active carbon media may lead it. In case the disease is seen in the tank and there are active carbon media in the filter, remove the active carbon media. Active carbon eliminates the minerals in the water column which some of which are toxic to fish but some others also necessary for the health of the fish. İt is recommended to use active carbon at the first setup for eliminating the heavy metals and other toxic elements to fish then remove it from the filter

Oscar fish suffers from Hole in the Head Disease the most. Most of the aquarists do not know how to keep the necessary environmental conditions of this fish at a good level that guarantees a healthy life for the Oscar fish.

Oscar fish can become quite large and they produce lots of waste which create high levels of ammonia in the aquarium. They need a large aquarium and frequent water changes and the most important is proper filtration to avert an increase in the level of Ammonia and cycle the Nitrogen properly. That kind of high waste and unhygienic conditions can cause not only HLLE but many other diseases as well and it is a serious problem in the aquarium.


As the causes of HLLE are not specific, the treatment can vary. If one treatment does not work, the other option may make a certain change. That is why a wide range of anti-pathogenic medicines is available for treatment. Most aquarists prefer those formulas that contain metronidazole in their active ingredient.

If your fish tank happens to have activated carbon, remove the fish from it immediately and make water change. This will improve the nutrient levels and the disease will not aggravate. Also, an increase in the nutrition level can benefit the affected fish.

Vitamins can be helpful to sick fish. You can give them to fish by soaking the fish food in some liquid vitamin supplements to support their immune system. All bloodworms, pellets, mealworms, and other food can easily be soaked in vitamin liquids. While vitamins are vital for healthy fish, they can also harm the fish if given in more than the necessary amount. It is better to give in small amounts and observe the effects while keeping it regular.

Improve the water quality even if the dropping water quality is not the reason but you may never know what cause can become a trigger at any time. Moreover, poor water quality is one of the major causes of the disease Hole in the Head. It is the first and easiest factor to eliminate while starting the treatment.

Starting the treatment as soon as you realize that any fish is showing the symptoms of HLLE. Only timely treatment can save the fish from dying. But if the scars have developed a deep and clear shape on the head and body of the fish as well, they may remain for the rest of its life even if the disease is treated.

Pop-Eye Disease


Image Source: https://worldbettas.com

Some types of fish have eyes that are naturally protruding. But, if this natural feature exceeds the normal level, this means the fish is not in its healthy condition. This syndrome has a name that directly describes it in condition and it is “Popeye” among the aquarists. In scientific words, it is exophthalmia or exophthalmos. This is not a disease in itself but an indication of a bacterial infection in another part of the body of the fish. The eyes swell and pop out. Sometimes the eye is cloudy because of the fluid that accumulates in the eye.

It is still not clear whether the vision of fish gets affected or it is a painful condition for the fish but it is not simple to find your fish with one or both eyes popping out.


Image Source: http://angloamericanoffice.com

Popeye is not a disease in itself but it is more a symptom. It shows an underlying bacterial infection in fish. Some fish have naturally big and protruding eyes like Telescope Goldfish called Demekin in Japan and Dragonfish in China, Celestial Eye Goldfish or Black Moor Goldfish. But other fish that do not have naturally protruding eyes and it is abnormal when they develop on one or both eyes swelling very obvious.

Sometimes the fluid from the behind tissues leaks into the eye making the appearance of the eyes cloudy or discolored. The eyes of the fish can suffer from an injury, too. Injury happens in case the fluids explode the eye.

A fish fight or scratching the eyes against fishnet while catching the fish or natural rocks in the aquarium can cause the eye to swell. But, this kind of injury displays a different look of the eye. You can see bloodstains in the eye or some other signs of an accidentally caused popped eye.

If the Popeye disease becomes severe, the eyes may rupture and the fish will not be able to see again even if it successfully recovers from the Popeye disease.


The most common cause of Popeye is an injury (not to the eye) to the body of the fish. The open lesion gives way to the bacteria towards the inner side of the body. The body sends out a defense force to fight the bacteria and for this, the body creates extra white cells. The excessive amount of the white cells travels in the body and reaches both or one eye. The extra number of white cells crowd the eyes and cause swelling. The eyes can become misty or discolored too.

Fish do not have eyelids. That is why it is quite possible that they get hit on their eyes during a fight or the eyes suffer from an ammonia burn. Ammonia is acidic and can easily burn the outer layer of the eyes. This burnt or damaged spot is a large opening for the bacteria to find their way inside the fish and cause an infection.

Fish are often exposed to a high level of ammonia in their water environment especially during their collection and transportation process. Fish are caught from natural water bodies and kept in stocking tanks where the conditions are not always ideal. In those tanks, the filtration and water changes are not regular in most cases. The preventive chemical treatment is also not provided. As a result, the ammonia level often shoots and causes Popeye disease in the fish.

When ammonia is the cause of Popeye, you can observe the fish moving its gills rapidly even while it is resting and no outside stimulation is involved. If immediate action is taken for the elimination of high-level Ammonia, the fish can be saved from a fully developed Popeye.


Taking steps to prevent the Popeye disease from happening is much easier and better for the fish. So, here are a few tips for prevention;

The root cause of Popeye in fish is bacterial infections, do your best to keep the fish tank clean and water regularly changed to keep the bacteria at bay. Use a very smooth net for catching and transferring the fish to protect its eyes or body from scratches. If a fish is injured for any reason, transfer it to a quarantine tank and keep it there and treat its injury until it is fully recovered. Then, transfer it back to the original tank.

As mentioned above, Popeye is not a disease but rather a symptom of a bacterial infection, which is underlying somewhere in the body of the fish. It is worth mentioning again that you should start the treatment as soon as possible since the infection may develop very fast.

You can initiate the treatment with a water filtration system and removal/reduction of ammonia as this is the most common cause. Several good broad-spectrum antibiotics can actively treat bacterial infection in the fish. Kanamycin, chloramphenicol and tetracycline can successfully kill the invading bacteria. The treatment takes less time and shows better results when it is started in an earlier phase. So, be very aware of your fish and their health by observing them closely.

Antibiotics can damage the biological filtration in the aquariums. That is why it is better to transfer the fish to a quarantine tank and treat the fish there until they gain their health again.

If you see that the entire fish in the tank need the treatment, first work on the removal of the ammonia from the tank with a good ammonia reducer. This will limit the causes of damage and will let the fish heal faster. Then, apply the treatment for the infection.

Once the treatment is completed and the fish is fully recovered, apply beneficial bacteria starter cultures to quickly recover the biological filtration. In case it is not available re-plan the feeding amounts by reducing them to provide some time for biological filtration to settle back to overcome the livestock load in the tank. Then increase the food amount gradually.

Swim Bladder Disorder


Image Source: http://galleryhip.com

The swim bladder is an important internal organ in fish. It helps the fish to maintain buoyancy control. It helps the fish to manage the balance in the water whether deep or shallow without exerting too much energy in swimming.

Any disorder in the swim bladder averts the fish to maintain its balance and buoyancy in the water. Swimming becomes difficult and abrupt for the fish. That is why swim bladder dysfunction is also called Floating Disorder. You can observe that the fish is behaving awkwardly in the water and cannot swim smoothly as usual.

Image Source: https://tanksandtantrums.weebly.com

Swim bladder disorder is prevalent in aquarium fishes. Betta and Goldfish suffer from it more. But any fish that has a swim bladder can have this disease. Many aquarists cannot figure out that their floating fish is having a swim bladder problem but consider it dead though it is alive.

Swim bladder disorder is curable and proper treatment is advised by the specialists to save the fish from getting into worse conditions.

Swim Bladder Disorder is not a disease but is a group of symptoms that occur in association with one another. In other words, it is a syndrome. Any injury, disease or disorder that causes a fish not to swim properly is listed under swim bladder problems. The treatment is possible only if you find out the underlying cause of the syndrome.


Symptoms are behavioral. The fish either floats on the surface of the water or sinks to the bottom heavily. If they swim, their movement is unbalanced like swimming sideways or floating upside down. The extra full or bloated look of the belly is quite obvious and the spine even becomes curved because of the bladder fullness.

Sometimes, fish swim horizontally like keeping their tail higher than their head when they suffer from swim bladder disorder. If this is not a usually natural behavior of your fish, then definitely the Swim Bladder Disease has set in.


There are many causes of Swim Bladder Disorder. You need to determine the root cause or the actual reason why the fish has lost balance or the ability to control buoyancy.

Pressure from other organs is the most common cause of swim bladder disease. The pressure of the internal organs significantly disturbs the function of the swim bladder. The fish loses buoyancy control. The pressure affects all the organs around the bladder and not necessarily the bladder alone. One cause is overeating which enlarges the stomach and causes pressure on other organs as well as the bladder.

Too many fatty deposits enlarge the liver which is another cause for internal body pressure over the other organs. Unhealthy growths like cysts may also enlarge the kidneys. A female fish can suffer from pressure when it deposits too many eggs. Constipation compresses the intestines which also causes swim bladder problems.

Internal infection from bacteria or parasites can also be a reason for the swim bladder disorder. Bacteria grow and reproduce in bad aquarium conditions. The quick action of cleaning and antibiotic treatment can remove the threat of swim bladder disorder.

A sudden injury or fall on the hard ground can cause a fish swim bladder problem. While transferring the fish, dropping on the ground which may hurt the fish internally is a possible cause. Active and aggressive fish can get hurt or hurt other fish which may become a reason for swim bladder problems as well.

Some newborn fish are unable to swim to the surface like livebearer species if the fry has genetically defected, it will show swim bladder problems. Some fry that comes out of eggs also can show signs of Swim Bladder Disorder.

Routine in the breeding of some fish like convict cichlids can also introduce deformed swim bladder in the newborn fish because of improper tank conditions and poor diet. In these cases, no treatment is possible and euthanasia is recommended for the fish with a deformed swim bladder.

In some cases, fancy verities of fish selectively brood like fancy goldfish and blood parrot cichlids grow into healthy adults but have a sensitive digestive system and suffer from frequent constipation. They need more fiber-rich food and should not be forced to live with aggressive and boisterous fish in the same tank. Physical injuries also affect them much more than other naturally breeding varieties.

Fish can lose mental balance after a sudden shock as it happens with the human. An abrupt change in the environment, a sudden transfer, or an exposure to an entirely different environment can make the fish go crazy for a temporary time. It may show the symptoms of Swim Bladder Disorder. A tropical fish also goes in shock if very cold water is added to the tank and may cause the same syndrome to come out. There is no treatment for this kind of disorder but just leaving the fish to rest and rebalance itself. Turning a few lights off to lower the brightness will help reducing stress. After spending some time in quietness, they will return to their normal behavior.

Some fish like cichlids involve in fierce fights. They are very much prone to have swim bladder problems. You cannot stop this cause or eliminate it but reduce the possibility by stocking the fish in a bigger tank and in fewer numbers to decrease the chances of fierce fights.

Parasitic worms can attack the fish in the aquarium. On the whole, they are not a common cause for swim bladder disorders except when their amount is excessive in the fish guts. This hampers the fish to swim smoothly.


Treatment largely depends on the cause. And diagnosing the real underlying cause is the most difficult phase of the treatment. Starting from physical symptoms to behavioral disorders, you need to examine the entire body and routine of your fish.

Injury: If the reason turns out to be physical, the treatment can be tough with a lesser chance of a full cure. But several treatment methods such like can adding antibacterial medicines in the fish tank or mix them with food until the physical injury is healed.

Overfeeding: Bloated belly which can be a result of overfeeding or wrong diet and often is hard to treat too. The first step is just to wait until the food is digested and the fish feels relieved from the bloating without any additional feeding in case it is related to only overfeeding. Magnesium Sulphate addition during this period can also help digestion and removal of the extra body fluids. To prevent such problems a general rule of feeding the fish with what they can eat within 2 -3 minutes is suggested. Also, all leftover food must be removed after this period. Feeding fish twice a day is an ideal routine. Increase it to 3 times or more with small portions in some special cases such as conditioning the fish for breeding or the fish has grown bigger and needs more food.

Usually, 2 to 3 days not feeding the fish brings their belly to normal size but if it does not, it is necessary to look forward to other possible reasons for bloating and as well as their swim bladder problem.

Some expert aquarists improve digestion by feeding the fish pea hulls. This has the perfect amount of fiber for the fish.

You may observe bloating despite feeding a small amount of food. In this case, check for the temperature of the water. Water temperature lower than 24-26 °C slows down the digestion system in fish, may cause bloated bellies and buoyancy problems. If you find water temperature low, increase it to the normal level for the fish and observe the changes in the digestion of the fish.

Infections: Water can be a cause of spreading infection in fish if its quality levels have fallen lower than the standard levels. To confirm the quality of water, check the filter and consider water changes. You can do a thorough cleaning of the fish tank but transfer the fish first into another tank and make sure that you clean the tank to an extent that possible bacteria and parasites are eliminated.

If you find your fish frequently suffering from Swim Bladder Disease, one of the two causes is responsible: irregular and improper feeding or bad water quality. Take instant action to correct these two.

0 0 votes
Rate This Page
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments