Fin rot causes a betta’s fins to look like they are ripping or melting away. The infection can be alarming, especially for new fish owners. The good news is that fin rot is treatable, especially when caught early.
Fin rot is prevalent in betta fish. They often live in small, cold bowls without filtration. The less-than-suitable conditions cause infection from the bacteria that causes fin rot.
Hobbyists can help their bettas heal by giving them healthy living conditions. Nutritious food and minimizing stress also work.
For more severe infections, medications and aquarium salt work wonders.
What Is Fin Rot?
Fin rot, also known as fin melt, occurs due to a gram-negative bacterial infection. More severe cases of fin rot often develop a secondary fungal infection.
There are three types of bacteria that generally cause fin rot. These bacteria are Aeromonas, Pseudomonas, and Vibrio.
Fin rot is pervasive in betta fish because of their large, delicate fins. It is most common in unhealthy tanks where the dirty water eats away, or melts, the fish’s fins. The breakdown begins at the edges, slowly progressing further down the fins.
Fins with severe rot may look ripped or bloody. Fin rot that progresses long enough can reach the body and cause the skin to decay.
Fin rot is particularly common in betta fish bought from large pet stores. The fish often sit in tiny cups of dirty, unheated water for a long time before anyone buys them.
Bettas may have ripped fins due to fighting, tail biting, or tears from sharp decorations. These injuries are not the same as fin rot. The injuries can develop into fin rot if they don’t receive treatment and become infected.
The Causes Of Fin Rot
The most common cause of fin rot is unhealthy living conditions. Bettas, in particular, often live in tiny bowls with no heating or filtration.
The bacteria that cause fin rot are often present in the water already. A healthy fish can fight off the bacteria so it doesn’t affect them.
A fish experiencing stress or illness has a weakened immune system. They can no longer fight off the bacteria, which causes them to develop fin rot.
Here are some things that can cause stress:
- A tank that is too small (under 5 gallons)
- High levels of ammonia, nitrites, or nitrates (lack of cleaning & filtration & overfeeding)
- Cold temperatures (Below 75°F (24°C))
- Wrong pH levels
- Nutritional deficiencies
- Overcrowding
- Aggressive tank mates
An Uncycled Tank
Poor water conditions are often a result of having an uncycled aquarium.
Almost everyone has heard the myth that bettas can live in small bowls.
Pet stores market bettas as easy beginner fish that need little care. Many beginners take bettas home without realizing what care they actually need.
Small bowls get dirty much quicker than larger tanks and are harder to keep clean. Many new owners do not put filters in their fish bowls.
Dirty, stagnant water is the perfect place for bacteria to grow and infect suffering fish.
The myth that bettas need little care is going away. Today, many new owners come prepared with heaters and filters.
Most of them have never heard of the nitrogen cycle, though.
The Nitrogen Cycle
The nitrogen cycle usually takes between two to six weeks and makes aquariums safe for fish.
Beginner hobbyists regularly buy their betta and tank at the same time. The tank has no time to go through the nitrogen cycle, which builds up beneficial bacteria. Good bacteria break down toxins and make the water safe for fish.
The water becomes toxic during the nitrogen cycle. High ammonia, nitrites, and nitrates are present in the water.
Bettas living in uncycled aquariums usually develop fin rot.
A Lack Of Nutrients
Bettas that don’t receive nutrient-rich foods will not be in the best health. Their immune systems suffer, and they cannot fight off pathogens like bacteria.
Bettas are obligate carnivores that need meaty, protein-rich foods to be healthy.
Choose flakes or pellets designed for bettas, as they have a high protein content. Avoid tropical fish foods because they don’t contain enough protein.
Give bettas a variety of foods. Switch up their flakes and pellets for some live, frozen (thawed), or freeze-dried foods.
Injury
Fin rot may develop from injury to the fins.
Sharp decorations and bullying from tank mates are common causes of injury. Their fin injuries are susceptible to infection without treatment.
How To Prevent Fin Rot
The best way to prevent fin rot is to keep the tank clean and ensure the water parameters are healthy and stable.
Prevent fin rot by doing these things:
- Use a filter to keep the tank clean and a heater to keep the temperatures warm
- Perform regular water testing and clean the tank at least once a week
- Hobbyists should feed their bettas healthy, protein-rich foods to boost their immune systems
- Avoid putting animals and decorations in the tank that may injure or stress the betta
- Aggressive or fin-nipping tank mates, like most barbs and tetras, are unsuitable
- Avoid decorations with sharp edges, like plastic plants
- Choose live or silk plants instead, as they are gentle on delicate fins
- Live plants are ideal for helping with the health of the water in the tank as well
Fin Rot Symptoms
Fin rot causes a betta’s fins to appear shredded or melted. How severe the condition presents depends on the infection’s progression and treatment.
Fin rot develops in three stages: Mild, moderate, and severe. How aggressively hobbyists treat fin rot depends on its current stage.
Fin rot is highly treatable, though it progresses quickly without treatment. The faster a hobbyist catches the deterioration, the easier it will be to help their betta.
Mild Fin Rot
New fin rot causes color loss and may appear white, brown, or red at the edges.
The fins appear somewhat frayed along the edges, though rot is minimal.
Moderate Fin Rot
As the infection progresses, the edges of the fins appear black or red and bloody.
The deterioration is more severe, causing the fins to look roughly jagged or ripped. The fins deteriorate in larger portions closer to the body. Bettas may begin to lose large chunks of their fins.
The fish may develop a secondary fungal infection, causing white, fuzzy growths.
Severe Fin Rot
Once the infection becomes critical, the base of the fins turns red from inflammation. The fins are often bloody, and the fish suffers almost total fin loss.
The white, fuzzy growth becomes more severe, often covering the remaining fins.
At this point, bettas usually struggle to swim. They are lethargic, spending most of their time at the bottom of their tank.
Columnaris
Severe fin rot can lead to Columnaris, another bacterial infection. Columnaris is more dangerous and harder to treat than fin rot. It can affect fish internally and externally and can kill quickly.
Body Rot
Fin rot that goes without treatment can progress to the fish’s body, causing its skin to rot. Once the infection reaches their body, it’s almost impossible to save them.
How Quickly Does Fin Rot Progress?
Fin rot progresses quickly, usually over a few days or weeks.
The worse the water conditions, the more quickly fin rot progresses.
A betta living in deplorable water conditions can develop severe fin rot in only a few days.
Is Fin Rot Painful?
Fin rot is painful for fish as their fins slough off their bodies.
Moderate to severe cases of fin rot often cause bleeding and fungal infections. Severe fin rot that spreads to the body is very painful.
Fish like to rub themselves against objects to relieve pain and irritation. Doing so often causes injury and more pain.
How To Treat Fin Rot
The good news is that fin rot is highly treatable and rarely fatal.
Bettas with mild fin rot should heal quickly. They may not need medications, which can be harsh and stressful.
More severe fin rot needs drastic intervention.
Test The Water
Hobbyists should test the water no matter the severity of the fin rot. Toxicity in the water or unfit pH levels are one of the biggest causes of fin rot.
Fix the pH levels if they are too low or high.
Raise the temperature if it’s too low. Most bettas need a heater to stay warm enough; hobbyists that don’t own a heater will need to buy one.
Clean The Tank
Hobbyists should immediately do a 50% water change if any water parameters are unsafe.
Several daily water changes may be necessary to get the ammonia and nitrite levels down to 0 ppm. The nitrate levels should remain below 40 ppm.
Use a gravel vacuum to remove the water to get old fish food and waste from between the substrate.
Hobbyists should buy a filter and add it to the tank if they don’t already have one. They work wonderfully to remove toxins from the water and keep the tank healthy.
Testing the water and cleaning the tank is often enough to heal mild fin rot. Hobbyists will likely need to do many water changes over a week or two. It’s rare to fix high toxicity levels with a single water change.
Move The Betta To A Quarantine Tank
Moving the fish to a quarantine tank isn’t usually necessary for mild fin rot, though it can speed up healing.
Once the condition progresses, a hospital tank is the safest way to go.
It allows the hobbyist more control and is easier to keep clean.
Hospital tanks are usually smaller, reducing stress on bettas struggling to swim.
Equip the hospital tank with a heater and filter. Add a decoration(s) that isn’t sharp — it will provide a hiding space and prevent stress.
Move the betta to a hospital tank if they normally live with other fish, even if the infection is mild. Other fish can cause stress and may nip at the already injured fins, worsening the condition.
Mix Aquarium Salt Into The Water
Aquarium salt is beneficial regardless of the severity of the fin rot. It is necessary for all fish suffering from moderate to severe fin rot.
The salt promotes the production of the betta’s protective slime coat. It helps with healing and reduces stress.
Mix and dissolve the salt into new water before adding it to the aquarium. Follow the instructions on the package to know how much salt to use.
Be careful only to use products specifically labeled “aquarium salt.” DO NOT use table salt or salt used for saltwater tanks.
Don’t treat aquariums with invertebrates or plants with aquarium salt, as it will kill them. Move the betta to a hospital tank for treatment if their main tank has plants or inverts.
Use Medications
Antibiotic medications become necessary once the fin rot has become severe.
They can help moderate cases of fin rot, though it’s usually unnecessary for mild cases.
NEVER stop treatment early or skip a dose. Doing so gives the bacteria time to build up a resistance to the antibiotic.
Good antibiotics for fin rot:
- Maracyn ii
- Kanamycin
- Kanaplex
- Erythromycin
- Methylene Blue (for fungal infections)
Add an airstone to the aquarium to maintain healthy oxygen levels in the tank. Medications reduce the amount of oxygen in the tank.
The betta is likely to be struggling to breathe and swim at this point. It may not be able to get to the surface of the aquarium.
Remove any activated carbon from the filter, as it will remove medication from the water.
Indian Almond Leaves
Hobbyists can add Indian almond leaves to the water to promote healing. They release tannins, which are naturally healing and stress-relieving.
Simply place the leaves on the water’s surface or inside the filter.
Can Fin Rot Heal Without Treatment?
Fin rot will not heal without some kind of treatment.
Fin rot may be mild, and the caretaker may only need to clean the tank and change the water. That is still considered “treatment” and will help heal the fish.
Noticing a fish has fin rot and doing nothing to help their situation will not result in healed fins.
More often than not, the water parameters are off. The water parameters will not improve without intervention. The betta’s fin rot will worsen as a result.
How To Tell If A Betta’s Fins Are Healing
A betta healing from fin rot will not have any new damage. The rotting of their fins should stop.
A fish healing from fin rot will start to get its energy and appetite back.
It’s easy to tell if a betta’s fins are beginning to grow back because the edges turn transparent with new growth. The new fins will look healthy and uniform around the edges.
There won’t be any fraying around the edges like there would be if fin rot were still occurring.
The new growth on the fins is exceptionally delicate. Keep decorations to a minimum and keep the betta isolated to prevent injury.
Note that a betta’s new fins may not look exactly as they did before the infection. They may have a slightly different shape and may not be as long as before.
After Treatment
Fin rot may recur after treatment.
Treatment is stressful, and the new fins are delicate. It may take a few treatments for a betta to be completely healed.
Follow all the steps above to prevent fin rot from happening again.
Keep the tank clean and the water parameters healthy and stable. Avoid sharp decorations and nippy tank mates. Feed the fish lots of nutritious, protein-dense foods.
Is Fin Rot Contagious?
Fin rot is not contagious, though poor water conditions usually cause it.
It is likely that if one fish develops fin rot, the other fish are also experiencing stress. They will likely develop fin rot too.
FAQs
Why Do Bettas’ Fins Stick Together?
Fin clamping is a condition that causes a fish’s fins to stick together.
Like fin rot, fin clamping is a common symptom of poor water quality. Low temperatures, nutritional deficiencies, and other stressors can also cause fin clamping.
Why Do Bettas Bite Their Tails?
No one knows for sure why bettas bite their tails, though they likely do it because of stress.
Some hobbyists say they do it when they get bored.
Owners can try giving their fish a bigger tank and more decorations. These offer mental stimulation and may stop tail biting if the fish is bored.
