While every fishkeeper, dog owner and cat parent hopes that their beloved pet will stay in top health their whole lives, it's almost inevitable that, at some point or another, they will contract some infection, illness or disease. While the fluffy pet owners among us may be on the lookout for fleas and tics, when it comes to our water-dwelling friends it can be harder to know what common illnesses to be aware of.
One such commonly occurring fish disease is fin rot. An infection which can be potentially life-threatening when left to worsen, fin rot can be concerning for fishkeepers as it is dangerous and contagious, but our experts are here to reassure you that fish can recover from fin rot. The treatments that have been developed are quick and effective, and the steps you can take for preventative care are just as easy.
If you’re concerned that 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, read on to learn all the essential information you need.
What is fin rot in fish?
Fin rot is a bacterial infection which targets the fins and tails of aquarium fish. The bacteria is naturally occurring in fish tanks and is as unavoidable as the bacteria we are naturally exposed to in our own daily lives. However, not unlike when we get food poisoning, UTIs or ear infections, the fin rot bacteria can overwhelm the fish when it gets past its defences or its immune system can’t fight it off, infecting the fish.
What causes fin rot?
As with any other bacterial disease, fin rot is caused by a fish being infected by bacteria. In the case of fin rot, however, there's usually more than just the bacteria to blame. In most cases, the fish should have a sufficiently strong immune system to battle any bacteria it comes into contact with. If this isn’t the case, it's likely that one (or more) of the following environmental factors has stressed the fish and weakened its defences:
- Poor water quality - The most common cause of increased stress and lowered health for fish is poor water quality. Directly dependent on their environment being suitable for them, any changes in pH levels, water temperature, poor chemical balances, or heightened ammonia, nitrite or nitrate levels can have a dramatic effect on your tank inhabitants.
- Overfeeding - A bad habit shared by many beginner fishkeepers, overfeeding can lead to the excess food decaying, which will then cause water quality issues such as high ammonia levels.
- Poor diet - Just as we are encouraged to eat our greens to better strengthen our immune systems, a good diet will also go a long way in improving your fish’s resilience against diseases and infections. Make sure you’re using high-quality fish foods suitable for the species and nutritional needs of your fish.
- Tank mates - A fish’s immune system is directly linked to their stress levels. If there’s something in their environment that is causing their stress to increase, their immune system will suffer for it. Overcrowding or sharing a space with aggressive fish are common causes of heightened stress and should be avoided. Read our blogs on how many fish to put in an aquarium to make sure you aren’t overstocking your tank.
- Pre-existing injuries - If your fish has any nicks, scratches or tears on or around their fins or tail, they’re at a higher risk of infection. These are most commonly caused by aggressive fish nipping at them, or any mishandling during transportation or cleaning.
How do I know if my fish has fin rot?
Due to its characteristic appearance, fin rot is quite easy to identify and diagnose, especially on fish with longer, flowing fins and tails such as bettas, goldfish and angelfish. The tricky part with fin rot is catching it early, as the initial signs of infection can be quite subtle and hard to notice, such as faint discolouring and unusual swimming habits. Even so, familiarising yourself with the signs and symptoms can help you diagnose and treat fin rot in fish as early as possible.
What does fin rot look like?
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. Spotting the infection at this phase is difficult, but becomes easier as the following more easily recognisable fin rot symptoms start to appear:
- 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.
How to treat fin rot
In order to treat fin rot properly, you can’t just treat the infected fish and leave it at that. Instead, you also need to identify the root cause of the problem (whether that’s overcrowding, poor diet or bad water quality) and take steps to improve that too. Only from this joint approach can you be sure that your fin rot problem will go away, and stay away.
To make sure you effectively treat fin rot on the first try, we’ve added a step by step guide below on what you need to do.
Step 1 - Identify and eliminate the immune system threat
We’ve already laid out the main threats to a fish’s stress levels and immune system above, with poor water quality, overfeeding, poor diet, bad tank mates and existing injuries being the big five to look out for. These are all issues which can be avoided or rectified, with fixes and better habits easy to incorporate into your usual care routine. You can do this through the following:
JBL Test Combi Set plus NH4, £39.95
2. Perform a water change. If poor water quality is the cause of your fin rot infection, we also recommend performing a 25% water change. This can quickly improve the quality of your water, removing some of the impurities, debris and chemical imbalances your current tank water is suffering from. If you’re using tap water to complete the change, make sure this has been treated with a dechlorinator, such as the Fluval Aqua Plus Water Conditioner.
Fluval Aqua Plus Water Conditioner, from £27.99
3. Clean your tank. Perform a thorough clean of your tank, making sure to syphon any debris or waste from the gravel. This will help improve your water quality and stop it from worsening if any trapped organic matter starts to decay, and will help lessen the stress levels of your fish. If you’re not sure where to start for this, read our full guide on how to deep clean a fish tank for help.
Step 2 - Use a fin rot treatment to fight the infection
As a bacterial infection, the most effective way to fight off fin rot is to treat it with an antibiotic.
1. Pick an antibiotic treatment suitable for targeting gram-negative bacterial infections. As a common illness among home aquariums, many leading fishkeeping brands have developed these treatments, and they’re safe and easy to administer yourself. While any treatment that states it works against fin rot will be effective, our experts use Interpet’s Anti Fungus & Fin Rot treatment as it’s affordable, reliable and fast-acting. Waterlife’s Myxazin 500ml treatment is also a great choice for those treating larger tanks, while NT Labs’ Marine Anti-Bacterial treatment is suitable for marine and reef tanks.
Interpet Anti Fungus & Finrot 100ml+, £7.90
Waterlife Myxazin 500ml, £14.95
NT Labs Marine Anti-Bacterial Treatment 100ml, £10.39
2. Remove the active carbon from your filter before administering the treatment. This is because the media will absorb the antibiotic from the water before it can be taken on by the fish who need it, negating the effectiveness of the treatment.
3. Follow the instructions detailed on your chosen treatment. As doses and application times can differ from treatment to treatment, it's important that you follow the instructions to the letter to make sure the antibiotics have the best chance possible at working first time round. 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 - Prevent fin rot from coming back!
It's not enough to treat fin rot, you should also do everything you can to make sure that the infection doesn’t have a chance to come back. This is easy to do, and just comes with implementing proper maintenance and care to ensure that your fish aren’t exposed to any unnecessary stress. Things like implementing a proper cleaning routine, regularly carrying out water changes, using high-quality food and not overfeeding will go a long way to keeping them safe, healthy and happy in the long term.
Additional frequently asked questions about fin rot
Can a fish recover from fin rot?
Yes! Through proper treatment and careful aftercare through a better aquarium maintenance routine, your fish can recover from the damages caused by fin rot. In most cases, you’ll slowly see your fish’s damaged fins and tails begin to heal, with the process taking a few weeks after the treatment has started. It’s only in cases where the infection has rotted away significant portions (or all) of the fin or tail tissue that regeneration isn’t possible.
Is fin rot contagious?
Yes, fin rot can spread to other fish in your tank, but this isn’t always the case. 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 to other fish. However, if the cause was an injury on an individual fish caused by bullying and nipping from aggressive fish, it's unlikely to spread to those fish with stronger immune systems.
Diagnose, treat and prevent fin rot with help from Aquacadabra
As fishkeeping experts with decades of experience between us, our team at Aquacadabra is here to help you take good care of your aquarium, whether it's your first or your fifth! If you’re worried about fin rot and want some extra assistance, send us an email at info@aquacadabra.com or give us a call on 01322 520 989 to get some tailored advice.