betta fish with fin and rot loss taking a breath in aquarium

Betta Fish Fin Loss vs Fin Rot – What’s The Difference?

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Betta fish are known throughout the fishkeeping hobby for their beautiful colors and seemingly endless variations of form. But the betta’s trademark is his flowing finnage. These glamorous fish are certainly the supermodels of the aquatic world!

So, as you can imagine, discovering that your betta fish’s gorgeous fins are falling apart is a horror story for any owner! But what’s the cause of the problem? Well, a betta’s fins can be damaged by two conditions; fin rot and fin loss.

In this guide, we take an in-depth look at both of those problems. We tell you how to identify the cause of your pet’s condition, and we give you advice on how you can successfully treat it.

Fin loss vs. fin rot – what’s the difference?

Before you can set about helping your betta buddy, you need to know more about both these conditions. Making the correct diagnosis of the cause of the fin damage is extremely important, as the treatment for the two problems is completely different.

Fin loss

Fin loss is the term that’s used to describe a physical injury to your fish that may have been caused by your pet catching his fins on a sharp or rough surface. The damage can also be caused by fin nipping by another fish. Fin loss is basically caused when the tissue of the fin is physically torn.

Fin rot

Fin rot is caused by a bacterial infection that leaves the fish’s fins ragged and tattered. The fins can even appear blackened or bloody if the infection takes hold and becomes severe. Large pieces of the fins often fall off or rot away altogether.

All about betta fin rot

betta fish decoloration

So, fin rot is classified as a gram-negative bacterial infection, which is usually triggered by poor water hygiene or unsuitable parameters. Unfortunately, betta fish are very sensitive to water conditions, and that makes them especially susceptible to fin rot. In fact, along with constipation, fin rot is pretty much the most common disease that afflicts betta fish.

What triggers fin rot?

Fin rot is most often seen in uncycled or dirty aquariums where the levels of ammonia, nitrite, and nitrates are very high. Unstable water parameters, including temperatures and pH levels, can also trigger outbreaks of fin rot. Bettas are sensitive fish, and they are vulnerable to the stress that fluctuating tank conditions can cause. Stress weakens the betta fish’s immune system, making him more likely to succumb to bacterial infections, including fin rot.

Symptoms of fin rot

Fin rot is pretty easy to spot. Your betta’s fins will begin to appear ragged and frayed, and the ends of the fins may turn black or bloody. If you have a betta that’s very dark in color, those signs can be tricky to spot, so you’ll need to look closely.

Generally, fin rot symptoms do not include loss of appetite or inactivity, unless the disease is pretty far advanced.

Mild fin rot treatment for betta fish

If you think that your betta pet has fin rot, the first thing to do is to check the water parameters in your fishy friend’s tank. There’s no point in treating your betta fish if the root cause of the stress that’s brought about his condition goes unremedied.

So, the water temperature in the aquarium should be between 75o and 80o Fahrenheit, with a pH range of between 6.5 and 7.5, and a water hardness of between 3 and 4 dGH. Test the water right away to see if it could be that one of these elements is out of your pet’s preferred range. If you discover a problem, takes steps to remedy that right away.

Ammonia and nitrite levels should be zero, and the nitrates should be 20ppm (parts per million) or less. If these levels are too high, carry out a partial water change immediately and continue to monitor the water condition every few days, going forward. If the water parameters are unstable, it could be that your filter unit needs cleaning, or the cartridges may require replacement.

Generally, if the fin rot is quite mild and the damage is limited to less than half the fin, a water change and appropriately adjusted water parameters are the only treatment that’s needed.


It’s critical that your betta’s fins are not exposed to any further toxins while the damage is healing. New fin tissue is very delicate and fragile, and it’s common to see recurring infections and relapses even after the healing process has begun. So, be sure to keep a close eye on your betta fish for a few weeks following treatment.

Your betta fish’s fins may grow back slightly curled at the edges. Although that doesn’t always happen, it’s quite normal, and your fish will not be in discomfort.

Severe fin rot treatment

In severe cases of betta fin rot, you will need to treat your pet with medication, as well as making sure that his water is clean as outlined above. There are several effective gram-negative antibiotic products on the market that can be purchased over-the-counter in good fish stores.

Start by placing your betta in quarantine; if he lives in a community tank, you don’t want to treat the whole setup, as medicating healthy fish can be harmful. Begin by dosing the water in the quarantine tank with the antibiotic, following the manufacturer’s instructions carefully. Throughout your betta’s recovery period, make sure that you keep his water clean and with the preferred parameters, as mentioned earlier, and carry out regular partial water changes.

It can also be helpful to add aquarium salt to the tank, which may aid the recovery process. Again, follow the manufacturer’s dosage instructions on the product packaging.

Betta fin loss

Many concerned owners confuse mild fin rot symptoms with fin loss. However, the causes and treatment of the conditions are completely different.

What causes fin loss?

betta fish with plants in aquarium

Unfortunately, betta fish are very susceptible to fin damage.

Those glorious trailing fins are very delicate and can easily become snagged on sharp objects with the result that the fin tissue becomes torn as the fish pulls away to free himself. Also, if you keep your betta in a community tank, especially with species such as tetras, fin nipping can be a big problem.

Persistent nipping causes stress, leaving the betta open to attack by bacteria. Also, if the nipping is persistent, the betta’s fins will eventually become damaged and torn, leaving your fish at risk of contracting a bacterial infection.

Preventing fin damage

You can take steps to prevent your betta fish from injuring his fins by carefully checking any new items of tank décor before adding it to your pet’s tank. That includes plastic plants, driftwood, rocks, and betta toys. Even the substrate can be rough and potentially damaging to your fish’s fins, so be sure to choose gravel with rounded edges, or perhaps consider marbles or small pebbles as a smooth-sided alternative.

There’s a simple test that you can do to check that the decorations and toys you’ve chosen for your betta tank are safe for your pet. All you need to do is take a pair of pantyhose or nylons and run them over the items of décor. Provided that the nylon fabric doesn’t snag or tear, the item is safe for your fish. If you do discover any sharp edges, you can usually file away the rough parts, using a piece of sandpaper.


One big no-no is plastic plants. The leaves of plastic plants are typically hard and quite sharp, and that can easily injure your fish. So, choose silk plants or, ideally, living plants for your betta’s tank.

Live plants are the best choice for the tank, as they won’t hurt your pet, and they also help to improve the water quality in the tank by using nitrates as fertilizer and by removing CO2 and expiring oxygen. Also, live plants offer a surface on which beneficial bacteria can proliferate, helping to keep ammonia and nitrite levels down.

Broad-leaved varieties can offer your pet somewhere to rest, and floating plant species make an inviting site for bubble nest building.


Unlike Placats, betta splendens are not fast swimmers, largely because of their cumbersome, trailing finnage. So, if you do decide to introduce some company to the aquarium for your betta buddy, choose peaceful fish species that are not prone to nipping fins. For that reason, angelfish, barbs, and most species of tetras are best avoided in a betta tank. If you do spot any aggressive, nippy behavior going on in your betta’s tank, remove either the culprit or the betta right away before any damage is done.

Treating split fins

In cases of mild fin damage, the fin tissue will generally repair itself pretty quickly. Any small splits or holes will usually fix themselves without the need for any treatment at all. However, you must ensure that the tank water is kept clean when minor injuries do happen to prevent infection from developing.

It can also be beneficial to use a water conditioner that contains a slime coat booster or anti-stress additive, both of which may help to protect your betta from infections.

Final thoughts

If your betta buddy develops torn, ragged fins, he could be suffering from fin rot or fin loss.

Fin loss is generally the result of an injury that’s caused by fin nipping or snagging the delicate fins on something sharp in the tank. Fin rot is a disease that’s caused by bacteria.

In both cases, it’s essential to maintain excellent water quality in your betta’s aquarium by carrying out regular water changes and looking after the filtration system properly. Mild cases of fin damage will often clear up without any intervention from you, other than rebalancing the water parameters and reducing levels of ammonia, nitrites, and nitrates. However, severe cases of fin rot do require treatment with a suitable over-the-counter antibiotic product.

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