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Fin Rot in Aquarium Fish: Causes, Symptoms, Treatments & Prevention

There are many bacteria in your fish tank, which will not harm your fish normally, but if the immunity of your fish decreases, the bacteria will invade your fish’s body and cause diseases or even death. One of the most common diseases is fin rot, which will make your fish lose their beautiful fins. But luckily, this disease can be easily prevented and cured once you notice it early and find out the right cause.

So in this article, we will talk about why you fish get fin rot, the symptoms of fin rot, and how to cure and prevent it. Keep reading and save your fish from the pain of fin rot!


What will cause fin rot in aquarium fish?

Fin rot is caused by bacteria infection, and the bacteria infection happens when the immune system of your fish is damaged. So when we are discussing the causes of fin rot, we are talking about the reasons for immune system damage. The followings are the reasons:



Fish will get injured for some reasons. If the wound is not treated properly, it will get infected and damage the immune system of the fish, causing fin rot.



The capacity of a fish tank is limited and different fish need different sizes of fish tanks. If you put too many fish in a fish tank, they will get stressed. You should obey the general rule if you don’t know much about fish-keeping, which is one gallon of water for 1 inch of fish.

But it is not always correct, you should adjust according to the fish you are keeping in your aquarium.


Fin nippers and aggressive tank mates in the fish tank

Some fish are fin nippers that like nipping charming fish, which will cause fin rot of your fish. When choosing tank mates for your fish, you should avoid tetras such as serpae tetra and neon tetra, tiger barbs, cichlids, gouramis, etc.

You should also keep your fish away from some aggressive fish such as bettas because aggression will make them feel threatened, which will decrease their immunity and cause bacteria infection.


Poor water conditions

Fish are sensitive to their environment, if the water conditions such as temperature, pH level and hardness change, they will be stressed out and become ill, which gives chances to bacteria.

In addition, the toxins, including ammonia, nitrates and nitrites in the water will also affect the health of your fish.


Improper feeding

Feeding fish is not a difficult task but also not an easy one. Once you feed your fish that are not fresh or overfeed them, you’ll make them feel uncomfortable and be vulnerable to bacteria and finally get fin rot or other diseases.


Will all fish get fin rot?

Yes! Whether you are keeping freshwater or saltwater fish, none of them can get rid of fin rot if not being taken good care of.

But compared to those with small and short fins, Bettas, Guppies and Angelfish are more vulnerable to fin rot. The chances of them getting fin rot are higher. So if you are keeping fish that have beautiful, long and flowing fins, you should pay special attention to them.


The symptoms of fin rot

  • Lose color: the color of their fins will be faded.
  • Obvious spots: there will be some spots on their body and fins.
  • Incomplete fins: you can notice fraying fins.
  • Ragged edges: the edges of their fins will be while or transparent at the beginning, then the fin will fall off and the ragged edges show.
  • Inactive: stay in one place for a long time and move slowly.
  • Loss of appetite: refuse to take in food.


How to treat and prevent fin rot in aquarium fish?

Treatment of fin rot in aquarium fish

Before curing the fin rot of your fish, you should find out the exact cause and then suit the remedy to the case.


  1. You can start by checking if there are too many fish in your fish tank. As we mentioned before, there is a general rule for you. But in order to make it clear, you should find more information about the fish you’re keeping and find out whether you are overstocking your fish tank or not. If the tank is overstock, buy a new tank or remove some unnecessary decorations from your aquarium.
  2. Then you can check the water conditions in your fish tank. With pH paper, you can test if the acid level is suitable for your fish. Also, you should check if the ammonia and nitrate levels are above proof. If you find something wrong with the water, try to do a water change, but do not empty the tank, changing partially once.
  3. With a digital thermometer, you can find out if the water temperature is too low or too high. If the temperature is not suitable for your fish, use an aquarium heater to adjust and maintain the temperature.
  4. Observe the fish in your fish tank and find if there are some aggressive fish or fin nippers. Separate them immediately if you notice this happening.
  5. Check if the food for your fish is outdated and if they have taken in too much food. Feed your fish with some high-quality food to make up for the missing nutrients and take some methods to help them digest if you have overfed them.
  6. Use medicines. Ask your veterinarian for the medicines used to cure fin rot in your fish and follow his guidelines strictly.


Prevention of fin rot in aquarium fish

When you know how to treat fin rot in aquarium fish, you’ve already known how to prevent it since they are almost the same. And if you ask me for one efficient method, I will ask you to pay attention to the aquarium maintenance, which is vital to the health of your fish. The details are as follows:



Now you have known much about fin rot, you can start doing something for your fish. Go and observe if there are any symptoms that your fish are suffering from fin rot, if they are, try to use the methods we mentioned to treat your fish.

If luckily, they do not get such a disease, take steps to nip it in the bud. I believe you can protect your fish from fin rot and if you fail, I believe you can save them from it!



1. What are other common diseases in aquarium fish?

White spot, dropsy, velvet (rust/gold dust), ulcers, swim bladder disorder, cotton mouth, and so on.

2. What causes the death of a fish except for diseases?

Poor water quality, stress, overfeeding, overstock, insufficient filters, untreated water and improper water temperature.

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