Every pet owner wants to keep their beloved companions in peak health, but just like us humans, it’s almost inevitable that they’ll have an illness or ailment that leaves them under the weather. In that regard, fish are no different to other types of pets - but it can sometimes be more difficult to spot when there’s a health issue, and that’s why it’s worth brushing up on your knowledge of common fish problems, so you can swiftly tackle those pesky infections!
One of these common illnesses that are specific to our aquatic friends is fin rot - an infection that can become serious if not treated correctly. If you think your fish tank might be suffering from a case of fin rot and you want help diagnosing and treating the issue, or you’re just familiarising yourself with common fish issues so you can better your preventative care, keep reading to learn all about this disease.
What is fin rot in fish?
Fin rot is a bacterial infection, aptly named because it targets the fins and tails of aquarium fish. It’s caused by bacteria that naturally occurs in fish tanks, so exposure to it is unavoidable. Most of the time, it doesn’t cause any bother; however, when the fish are stressed or their immune systems are weakened, the bacteria can bypass their defences and cause infection.
What causes fin rot?
With the above point in mind that the bacteria is naturally occurring in tanks and therefore unavoidable, there are a few common issues that can make things worse or make infection more likely. This includes:
- Poor water quality - Fish need to be in a suitable environment to keep them healthy. This means that any changes in pH levels, water temperature, chemical balances, nitrate or nitrate levels, or high ammonia can cause the fish to become stressed or ill.
- Overfeeding - Overfeeding results in excess food decaying, causing poor water quality.
- Poor diet - High quality fish food will help improve the resilience of your fish, helping them fight against diseases and infections.
- Tank mate incompatibility - Being in an overcrowded tank, or a tank with aggressive fish will cause stress levels to increase, weakening their immune systems. (If you aren’t sure if your tank is overcrowded, refer to our guide ‘how many fish can I put in my tank?’)
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Pre-existing injuries - If your fish has any nicks, scratches, or tears on their fins or tail they will be at a higher risk of infection.
Is fin rot contagious?
Not exactly, fin rot can spread to other fish, but it is an opportunistic disease rather than a highly contagious one. Healthy, unstressed fish can fight off the bacteria quite successfully, but those with injuries, or in an overcrowded tank will find themselves with fin rot quite quickly.
In summary, how contagious a fin rot outbreak is depends on the immune system of the other fish. As such, if the root cause of the infection is tank-wide (such as poor water quality), it's more likely to spread.
What does fin rot look like?
Fin rot is quite easy to identify and diagnose, especially on fish like bettas, goldfish, and angelfish that have long, flowing fins. Though, the initial signs of infection can be quite subtle and hard to notice, such as faint discolouring and unusual swimming habits.
The earliest signs of fin rot include discolouration of the edges of the fins and tail, turning the skin a milky-pale tone which slowly spreads inwards. As the infection advances, you may notice:
- Fraying edges on the fins or tail where the infected skin is worsening
- Ragged and split skin where the fins or tail have begun to die and flake away
- Inflamed and red skin at the base of the fins and tail
- Rotting of the fins and tail, leading to complete loss of the limbs if not treated
- Behavioural changes, including lethargy, loss of appetite, and sitting at the bottom of the tank
- Black, white, or brown spots on the fins, tail, or sometimes the body.
How to treat fin rot
In order to treat fin rot properly, it’s not a case of just treating fish that are visibly showing the infection. You also need to identify the root cause of the problem and take steps to improve that too. This will ensure your fin rot problem will go away, and stay away.
Step 1 - Eliminate the Root Cause
The first thing to check is your water quality. Any imbalances in your aquarium water can be identified by performing a simple water quality test. If your water falls outside of the recommended boundaries for any of the measured quality parameters, you can use the corresponding water quality treatment.
If you do find that poor water quality is the likely culprit causing your fin rot infection, we also recommend that you perform a 25% water change. This can quickly improve the quality of your water. If you’re using tap water to complete the change, then you should make sure this has been treated with a dechlorinator.
We also recommend that you deep clean your tank. You don’t have to remove your fish or your water to perform a sufficient deep clean, but you will need to clean your gravel, ornaments, glass and decorative plants. If you’re not sure where to begin, you can read our dedicated how to deep clean your fish tank guide.
*Whilst water quality is a likely culprit, you also need to check for overcrowding, overfeeding, and tank mate incompatibility.
Step 2 - Use Fin Rot Treatment
Improving the water quality is a great first step, but fish that have already contracted the infection are likely to need a little extra help with the use of an antibiotic treatment.
As a common illness among home aquariums, many leading fishkeeping brands have developed suitable treatments that are safe and easy to administer yourself. We have a wide range of fish medicines available to help you find an appropriate solution. However, our recommended product is the Interpet Anti Fungus & Finrot 100ml+ as it’s affordable, reliable and fast-acting.
*Waterlife’s Myxazin 1L treatment is also a great choice for those treating larger tanks or ponds, while NT Labs’ Marine Anti-Bacterial treatment is suitable for marine and reef tanks.
You will need to remove the active carbon from your filter before administering the treatment to stop the media absorbing the antibiotic from the water before it can be taken by your fish.
Always follow the instructions detailed on your chosen treatment,as doses and application times can differ. As with human antibiotic courses, you should also make sure to give all the doses needed, regardless of whether or not the fish start to look better before the course is finished.
Step 3 - Prevention
The final step is making sure the disease doesn’t return. This involves things like implementing a proper cleaning routine, regularly carrying out water changes, using high-quality food and not overfeeding. All of these things combined will go a long way to keeping them safe, healthy and happy in the long term.
Keep your fish healthy with Aquacadabra
Through proper treatment and an improved aquarium maintenance routine, your fish can recover from the damages caused by fin rot and, in most cases, you’ll slowly see your fish’s damaged fins and tails begin to heal (in cases where significant damage has occurred, regeneration may not be possible). Hopefully our guide has set you on the right path for administering treatment and restoring the health of your tank.
If you find yourself in need of extra advice, our team has decades of experience and are always on hand to offer advice, just contact us to find out more. If you’re just looking to brush up on your knowledge, our blogs also offer further advice on other common issues such as ‘how to treat white spot’ and ‘how to look after your tropical fish’.