Columnaris disease, otherwise known as cotton wool disease is a common but often misunderstood illness. It frequently attacks freshwater fish, particularly if they already have compromised immune systems.
What makes this disease so tricky is the fact that it exists in multiple strains, and is caused by a bacteria found in virtually all freshwater tanks. However, knowing how to prevent and treat columnaris disease in your fish can go a long way. Read on to learn more!
What Is Cotton Wool Disease In Freshwater Fish?
Columnaris, colloquially known as Cotton Wool Disease or Saddleback Disease, is a bacterial infection typically found in fish with compromised immune systems. It is caused by the bacteria Flavobacterium columnare and is a common disease among freshwater fish.
Left untreated, this disease is highly infectious and potentially fatal. Many fishkeepers shudder at the thought of an unchecked columnaris infection. Fret not, though – this article details how you can treat and prevent columnaris outbreaks in your tank!
Difference Between Columnaris And A Fungal Infection
Columnaris, or Cotton Wool Disease is often mistaken for a fungal infection, but this is not the case. Cotton Wool Disease is a bacterial disease caused by columnaris bacteria. Though columnaris may sometimes resemble a fungal infection, it is critical to differentiate between the two for effective treatment.
Cause
Columnaris
A type of bacteria known as Flavobacterium columnare
Fungal Infection
Two possible types of fungus: Saprolegnia and Achyla
Color
Columnaris
Depending on the strain, lesions can appear white, orange, yellow, or brown
Fungal Infection
White or gray
Texture
Columnaris
Initially, the disease looks like flat, pale patches on your fish’s body. As the disease progresses, it takes on a fuzzier appearance
Fungal Infection
White fuzz resembling bread mold
Microscopic View
Columnaris
Rod-shaped bacteria separated into tiny haystacks
Fungal Infection
Tendrils overlapping with one another
Now that we’ve learned how to differentiate between columnaris and fungal infections, let’s take a closer look at how to detect, treat, and prevent cotton wool disease in freshwater fish.
Symptoms Of Cotton Wool Disease In Freshwater Fish
Time is of the essence when it comes to cotton wool disease. The sooner you spot the symptoms of columnaris, the better your odds of treating it. Here are a few tell-tale signs that your fish may be sick:
Physical Signs
True to its name, the key physical sign of cotton wool disease is the presence of discolored white, yellow, or green lesions on fish fins, bodies, and mouths. These patches appear flat initially but may take on a ragged and fuzzy appearance as the disease progresses. It is at this stage that columnaris is often mistaken for a fungal infection.
You may also observe exposed flesh and muscle on your fish’s body. This is typically caused by excessive rubbing against jagged surfaces to quell the itching caused by columnaris. Ragged fins resembling fin rot are another telltale indicator.
Behavioral Changes
Quick-acting strains of columnaris disease typically kill their victims in 48 hours, meaning that fish owners might not get a chance to observe behavioral changes. However, slow-acting strains kill fish by gradually affecting their gill tissues. This causes several behavioral changes as the disease progresses.
The key sign to look out for is breathing difficulties. Some fish may move their gills quicker or gasp for air at the surface of the tank in an attempt to breathe. Scratching is yet another indicator – fish may swim against objects to alleviate the itching caused by columnaris.
Other behavioral changes one might observe include lethargy, loss of appetite, and difficulty in swimming. However, these are symptoms that are common in many aquarium diseases and should be assessed against other indicators of the illness.
Causes Of Cotton Wool Disease In Freshwater Fish
Here’s one thing that needs to be made clear about cotton wool disease – it is caused by a type of bacteria that already exists in every tank! Under most circumstances, these bacteria are harmless. However, a few factors may cause these bacteria to infect a host fish with columnaris disease.
Weak Fish
Fish that are already weakened by another illness or infection are more likely to get cotton wool disease. An existing illness causes the fish’s immune system to be compromised, increasing the likelihood of secondary infections such as those caused by the columnaris bacteria.
Fish that are malnourished, or kept in less-than-ideal water conditions may also lack the strength and immunity to fend off cotton wool disease. Fish that have been selectively bred for multiple generations, such as neon tetras also tend to have immune systems that are lacking.
Poor Water Quality
Subpar water quality creates conditions that allow columnaris bacteria to thrive while putting the health of your fish at risk. Fish that are kept in poorly maintained tanks are more likely to contract illnesses, which in turn increases the odds of a secondary columnaris infection.
Furthermore, columnaris bacteria can be found in areas with a high density of organic waste. To lower the concentration of organic waste in your tank, perform frequent water changes and remove solid organic waste, such as fish droppings or uneaten food.
Contact With Infected Fish
Columnaris disease is highly infectious and can spread between fish. Certain strains are more infectious and deadly than others. Given the risk of a widespread infection, the best thing to do is to isolate all sick fish to protect the other occupants of the tank.
Another common mistake is adding new arrivals to your main tank without quarantining them prior. Fish from pet stores are typically kept in large groups, where the risk of cross-infection is likely. We know you’re excited to introduce your new fish to its home, but be patient! Quarantining new fish can save you a lot of heartache down the line.
Diagnosis Of Cotton Wool Disease In Freshwater Fish
The most reliable way to accurately diagnose cotton wool disease is to pay a visit to your local veterinarian. Your fish will need to be sedated, and a small scraping of the lesion will need to be obtained for a biopsy.
When examined under a microscope, the differences between cotton wool disease and a fungal infection will be immediately apparent. In the case of the former, your vet will observe distinct columnar structures, grouped into separate piles. Meanwhile, a fungal infection will feature a mass of overlapping filamentary structures known as hyphae.
An accurate diagnosis of columnaris is important so that you can administer the appropriate antibacterial treatment. Wrongly dosing your tank may wipe out beneficial bacteria, leaving you with a compromised biological filtration system!
Treatment Of Columnaris In Freshwater Fish
Now that you’ve accurately diagnosed your fish with columnaris, you may now proceed to find the best treatment for your fish. So – how do you get rid of this pesky bacterial infection? Check out our suggestions!
Isolate The Sick Fish
The first thing you should do is set up a hospital tank. Columnaris is a contagious disease and a hospital tank would prevent the disease from spreading to other fish. It also creates a safe, stress-free environment for your sick fish.
Hospital tanks also make medicating significantly easier and cheaper. The antibiotics used in treating columnaris disease can harm the good bacteria in your tank and destroy your nitrogen cycle, so it is best to medicate your fish separately. Furthermore, a hospital tank is also cheaper to medicate than a full-sized display aquarium.
Medicate Your Fish
Severe cases of columnaris will require antibiotic treatment. Because there are many strains of columnaris disease, you may need to enlist the help of a vet to identify the specific strain of bacteria causing the illness, as well as prescribe specialized antibiotics.
Under some circumstances, broad-spectrum antibiotics such as Terramycin and Acriflavine may be effective. However, seeing a vet significantly increases your fish’s odds of getting the treatment it needs.
Does Salt Help?
Depending on the type of fish, salt may be beneficial in columnaris treatment. Salt can speed up the process of healing, as well as alleviate some of the osmotic stress exerted upon the fish. However, you should avoid using salt for scaleless fish, such as the corydoras catfish and most types of tetras.
Adhere To Hygiene
Keeping your fish tank clean significantly increases your fish’s odds of recovery from columnaris. Because columnaris disease affects stressed-out fish, a clean tank promotes recovery by eliminating environmental stressors. Test your water frequently to ensure that you are on track.
How To Prevent Cotton Wool Disease In Freshwater Fish
Keeping your fish happy and healthy is the best way to prevent cotton wool disease. Fish with strong immune systems are better able to fend off pesky bacterial infections, so make sure you feed them a good-quality diet!
Columnaris bacteria also have a soft spot for organic waste, so you should make sure that you keep your tank in pristine condition. Test water parameters regularly and be thorough with tank maintenance! Organic waste tends to accumulate in filters and substrates, so be sure to attend to every component in your tank.
Another way to prevent cotton wool disease is by preventing infected fish from spreading the disease to their tankmates. Quarantine all new arrivals to ensure that they are healthy, and place all sick fish in a hospital tank. Better to be safe than sorry!
Conclusion
Cotton wool disease may be a common illness, but the good news is it is very easy to prevent! Just be sure to keep your fish’s habitat clean, and pay extra attention to fish that may already have compromised immune systems.
If your fish catches columnaris disease, know that it can be cured. Early detection is key, so be sure to keep a lookout for symptoms such as rapid breathing, and discolored lesions. Catch it early, and treat it effectively!
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