Fish rot is a common ailment in freshwater aquarium fish and mostly affects species with long, flowy fins and tails including betta, fancy goldfish, guppies, angelfish and a couple of cichlids.
Most times, the infections develop in poorly kept fish tanks. But it’s also quite common for fish bought online (or pet stores) to carry the ailment into healthy aquariums.
Fin rot infections vary from mild to severe, and it is common for hobbyists to miss it at first or take it to be regular fin nipping.
Therefore, to eliminate the doubt, fin rot is when your fish fins or tails tissues rot and the flippers start to fall away from their bodies. Most of the time, the fins also get rugged and have fluffy-like patches forming on the fish bodies, which is usually fungi that look like cotton wool.
The fish’s tail will also look like it’s shredded with chunks missing and the remaining part will become considerably weak.
Fin rot thrives given many varying conditions ranging from poor water quality, stress in the fish, poor handling, an aquarium being too hot or cold, overfeeding to your fish coming into contact with another fish with fin rot as it is contagious.
Even so, fin rot is generally caused by different types of gram-negative bacteria including Aeromonas, Pseudomonas, and Vibrio, all of which thrive in the conditions mentioned above.
The bacteria overgrowth and spread is however much more common in aquariums with poor water quality.
Please note I’m not a veterinarian, and I’m just passing on my experience and things I’ve learned over time mostly from the internet and while keeping fish.
How to Treat Fin Rot
The first step of treating fin rot is to improve the water chemistry quality in your fish tank, although you will need to move the infected fish because the ailment, as I have mentioned, is contagious.
To improve your water quality, change it after fully cleaning your fish tank making sure you get to wash dirt on glass surfaces, substrate and decorations.
If the disease is severe, you may want to re-tank all fish, empty and fully clean your tank completely before putting the fish back.
Once you set up the aquarium after cleaning, make sure your water parameters including the temperature and ph are appropriate for the kind of fish you are keeping.
You can add antibiotics to the clean water or add aquarium salt to help soothe the fish, treat the infection and prevent fin rot in the future.
Remember fin rot is easy to cure if it is caught early, but severe cases should be treated with antibacterial fish medication.
Ideally, fins that are seemingly melting away and falling off in big pieces or rotting close to the body should be considered quite severe.
Fin Rot Medicine
After cleaning your aquarium and adding your fish, you will most likely have a poorly fishy either in the usual tank if not severely infected or in a quarantine tank depending on the extent of the fin rot.
So, its recommended you get fin rot medicine for your fish from your local pet store or online.
You can choose from a variety of fish antibiotics, particularly antibacterials and antifungus, which are formulated to help control the fin rot causing bacteria.
However, it’s important to note that products like Bettafix, Melafix, and Primafix are not formulated to cure fin rot in particular and may actually make it worse.
This types of antibacterial medications are made to treat general sing of wounds, ulcers, mouth fungus, slimy patches, and cottony growth.
Even so, some aquarist have had success with them and are especially good for fish fin and tail regrowth and skin restoration including bringing back the fish coloration.
Moreso, when treating your fish for fin rot, it’s also important to determine whether there are any secondary bacterial or fungal infections away from gram-negative. The accompanying ailments are usually indicated by cottony growth or bloody patches on the fish’s body.
Can You Treat Fin Rot with Aquarium Salt?
Heavy fin rot medications have a quite a couple of negative side effects like bacteria becoming resistant, the fish getting extra stressed and most medicines are basically not safe for inverts.
Hence, in less severe cases of fin rot, you can treat the fish with a combination of clean water and aquarium salt which have less side effects.
However, the effectiveness of using aquarium salt is dependant on the stage of illness, where it’s less effective in serious cases. So try to catch the disease early enough.
To treat your fish with aquarium salt, use a 1 tablespoon of the salt per gallon of water for mild fin rot and 2 to 2.5 tablespoons per gallon of water for moderate cases.
Therefore, if your tank is 10-gallons, you’ll need to use 10 tablespoons of salt for mild infections and 20 tablespoons to treat moderate fin rot extent.
Before placing the salt in your fish tank, pre-dissolve it in a separate container and then add equal parts of the solution in 1-hour intervals till all the contents are in the aquarium.
Leave it in your tank for 24 hours then change 100 percent of the water and replace it with conditioned tap water of the same temperature as before and check all parameters are stable.
You can keep repeating the process for a week and a half but make sure your fish are not suffering from any negative effects caused by the added salt.
That being said, it is better to use salt in a quarantine tank to treat only the affected fish then re-introduce them back to the main aquarium once they are healed.
Moreover, if you keep repeating this process for a week and a half and not see any change, you are probably dealing with a persistent case of fin rot, in which case, you may have to treat it with medicine.
Can Fin Rot Heal on Its Own?
While fin rot can be due to many things, it is mostly caused by gram-negative bacteria hence the infection rarely disappears on its own, so its recommended to always treat an infected fish.
Moreover, while fish with a healthy immune system and pristine water should technically be able to get rid of the infection on its own, the system is mostly weakened by the fish rot. Hence other, more potent infections frequently develop.
Even so, there is a chance fin rot can go away if you catch it early and eliminate the cause.
For instance, you can clean your aquarium and make sure the water parameters are stable for the fish you are keeping.
Moreover, if you are not comfortable medicating your fish, try treating them with aquarium salt.
Fin Rot vs Fin Nipping
Fin rot is a disease that could make your fish unable to move if not treated promptly. So, being able to identify what fin rot looks like, along with knowing how to treat it will help you better care for your fish.
Even so, its not uncommon for fish keepers to assume a fish suffering from fin rot is merely dealing with a common fin nip, especially during the early stages of the ailment.
Thus the only way to be sure is by looking at the sings.
For instance, a nipping is just that; nips on the fin. It should not look white, red, black or any other color other than the fish’s natural color.
On the other hand, fin rot can be white around the edges, while black is a sign of ammonia poisoning and red streakings could be a bacterial infection that is pretty serious.
Another helpful hack is to look at the shape of your fish fins. Mostly, fin rot will affect the tail fin, but can also affect other fins though less frequently.
In the early stages of the fish rot, the edges of the fin will look rugged or shredded due to a breakdown in the fish protective membrane.
As the disease progresses, an increasing amount of the fin will be destroyed and will erode and resemble a semi-circular bite shape.
The fin may also develop a hole in the affected fin which is consistent with a fungus coming along with the fin rot, whereas hole will never appear in the case of fin nipping.
Keen observation of your fish colors can also be a reliable way to distinguish fin rot from nippings, with fins affected by fin rot becoming discolored.
Lastly, examine the entire body of your fish. In most cases, fin rot will affect other parts on your fish’s body, but nippings don’t.
For example, your fish may develop abdominal swelling, and you will notice ulcers and lesions on different parts that are not consistent with nippings.
Besides, if you don’t have aggressive fin nippers in your tank, there is no reason why you should have a fish with bites to big to the extent you are confusing them with fin rot.
Will Fin Rot Kill Your Fish?
There is a low likelihood that fin rot on its own will kill your fish, especially if the disease is detected early enough. However, severe fin rot may incapacitate your fish to an extent it cant swim even to get food. Hence generally become stressed and lethargic and easily take a toll on the fish.
Also, the infection affects a fish immune system, which means it becomes less resistant to other, sometimes more serious, infections.
Because of this, it’s common to have a fish with fin rot along with a fungal or bacterial infection which is potentially fatal.
Most of the time, these infections manifest on the fish body, appearing reddish or cottony-growth, though other times they show up on fins boring holes on the flipper tissue.
It is also important to note that fin rot left untreated will progress through the fin tissue and reach the body and consequently kill your fish.
Do Fins Grow Back After Fin Rot?
Fin tissue can grow back if the fish rot is treated before the fin rot grow down to the body and the water quality in the fish tank is kept in check.
Unfortunately, if the fin rot eats away the fin tissue up to body level, there is little chance for the fin to grow back. Plus the disease can enter the fish body and kill it.
That said, though medicines Melafix and Bettafix are not ideal for fin rot treatment, they help in fin re-growth, so consider using them after your fish have recovered.
Is Fin Rot Contagious?
Fish rot is generally a contagious disease caused by bacteria, so your entire tank is best treated to ensure the problem is dealt with ones and for all.
In fact, if one of your fish is infected, there is a chance others are infected too, just that the signs haven’t started showing.
However, the issue is highly preventable and if not introduced by new addition, then most certainly it’s caused by an issue within your aquarium set up.
Hence, equally important to medicating, is the evaluation of the fish tank to identify the cause and other cases of infection.
It is also recommended you quarantine the affected fish if you are sure others are safe and your water is pristine.
Good luck with the treatment, and enjoy fish keeping