Cotton fin fungus is a condition that typically affects aquarium fish with weak immune systems. The condition also goes by the name “Cotton Wool Disease”, characterized by the cotton wool growths on different parts of the affected fish.
Although fairly common, it’s important to address the condition immediately before it can cause much damage. Without proper care, the disease could kill off all the fish in the tank due to its contagious nature.
What Causes Cotton Fin Fungus In Fish?
There are multiple possible causes of cotton fin fungus and it’s crucial for aquarists to identify each contributing factor to the condition. Only through this can the problem be addressed one by one, hopefully treating the condition completely.
As the name suggests, the condition starts from the presence of fungi. With proper aquarium care, fungi should be kept at a minimum, but it isn’t always completely eradicated.
For the most part, fungi are kept at bay by the healthy immune system of the fish. Some factors, however, increase the chances of them multiplying and taking hold of the tank:
1. Weak Fish
Sometimes, all it takes is a vulnerable fish for the condition to swoop in and take hold. Even if you have excellent tank maintenance, old fishes or those suffering from an injury could contract the fungi and eventually affect everything else in the aquarium. Note that bullied fish or those that seem to be the subject of fights can also easily contract this problem.
2. Poor Water Quality
Make sure that your water quality is on point, providing the perfect environment for the fish to thrive in. This involves temperature control, oxygen; the cleaning chemicals added in and of course – the filter. The filter especially needs some attention because this is essentially the one ensuring that the water remains fish-friendly.
3. Improper Cleaning
How often do you clean your water tank? Keep in mind that water changes in tanks must be done partially instead of completely changing the water. The cleaning itself must be routine and involves all the crucial parts of the aquarium, especially the filter.
4. Decomposing Material
Cotton fin fungus has a way of latching onto any organic material and using this for food. If your aquarium is home to other organic materials that are no longer thriving, it’s probably a good option to take it out and throw it away. All it takes is one food source for the fungi to grow and afterwards – this would make it easier for the growth to spread to other fishes.
What Are The Physical Signs of Cotton Fin Fungus?
The most obvious sign of cotton fin fungus is a cotton-like growth on the body of the fish. The cotton usually starts from any open wound or damaged layer of the skin. From here, it can quickly spread to other body parts as the fish become weaker, essentially making it easier for the fungus to spread around.
Other than this, however, there are no other physical signs of the disease.
The main problem with the cotton wool disease is that it doesn’t have any behavioural signs. For the most part, affected fish act fine until the cotton wool actually appears on the surface of the skin.
Some preliminary behavioral signs may be noticed such as lack of appetite and lack of socializing – but this can be tough to notice at first. Should you managed to see these behavioral changes however, there’s a good chance that the fish is suffering from some kind of problem – not necessarily cotton fin fungus.
How To Treat Cotton Fin Fungus
Unfortunately, treatment can only be started once the condition becomes evident. Hence, there’s really no way of ‘catching’ the problem before actual health problems show up.
The good news is that there are several treatments you can use, starting from the natural to over-the-counter medications. Following are just some of your treatment options.
Isolate The Sick Fish
Obviously, your first step here is to isolate the infected fish, bearing in mind that the fungus is contagious. Once you’ve managed to separate the infected fish, it’s time to try different treatment approaches.
Tea Tree Oil For Cotton Fin Fungus
Tea tree oil is an excellent antifungal remedy although the consistency of the results isn’t assured. Studies show, however, that adding a few drops to the containment tank on a daily basis can help kill off the fungus.
Tea tree oil can also be used as a preventive measure when applied to a healthy tank. The beauty of this remedy is that it doesn’t affect sensitive species of fish.
The tea tree oil that we use on a regular basis is Handcraft Essential. We have seen a huge decrease in cotton fin fungus problems in our fish after adding just a few drops to a quarantine tank or our main aquarium.
Does Salt Help?
Fungi are incapable of tolerating aquarium salt so adding some in the water will slowly kill off the growth. Be careful with the application, though.
Make sure to check how much salt you can add based on the amount of water you have in your tank. Keep in mind that different species of fish have different levels of tolerance with salt.
Goldfish are pretty safe and can take high levels of sodium, but other species are less tolerant and might die rather than recover from the salt. Do your research, paying close attention to the breed of your fish.
The aquarium salt that we always have in our cupboard is API Aquarium Salt. It comes in handy on many occasions so it’s always an essential staple in our fishkeeping arsenal.
Medications For Cotton Fin Fungus?
You’ll find that pet shops are also full of liquid medications especially addressing cotton fin fungi. If you prefer a more targeted approach to the problem, this is perhaps your best option.
The product we recommend is API Melafix Antibacterial Fish Remedy. We have used API antibacterial products for years and we have heard nothing but good reviews from other people too. Again, a good antibacterial remedy can be used on several different occasions, so it’s always recommended to have a bottle or two on hand.
Adhere to Hygiene
Of course, don’t forget to go back to basics – specifically, cleaning the tank and making sure that the environment remains healthy for the fish. Once your pets show signs of cotton fin fungus, it’s best to check all your resources to see if they’re still on point – especially the filter.
Check out our starter guide section for more information on the basics of fishkeeping and overall aquarium health.
Cotton fin fungus is a deadly condition that needs to be addressed as soon as it appears. Keep in mind that when it comes to tank diseases, prevention is definitely better than cure. Hence, take the time to use natural preventives like tea tree oil instead of simply addressing the condition once you notice the signs.
Eggs may also be infected with cotton fin fungus. If this happens, there is no other known remedy so just make sure that the eggs are thrown away.