betta close-up, originally uploaded by Stephie189.

Q: SU wrote:

I am a college student at Radford University. My poor betta has developed fin rot. I have had my betta for almost a year now. He has had ich before and has cleared up fine. But now he has fin rot. I first thought the light red was the color at the ends of his fins due to his mixture of color but I was wrong:( Now his back fin is all torn up and is almost half the original size. I sorta see what i think to be re-growth but the inner side of the fin still is really red. He lives in a one gallon tank with a light and the temp stays around 76-78.I do a 50% water change every week then do a full change a week later.I always use spring water to fill his tank. He has been fighting fin rot for about a week now. I am currently treating him in a smaller tank. Im using BettaFix and also keep aquarium salt in his tank. He hasnt lost his color or appetite. Im just so worried about him. Im away from college and have no car if I have to go get more meds for him. Any more ideas?

A: Fin rot is a bacterial infection usually caused by poor water conditions. We tend to see it more often in smaller, uncycled bowls without a filter or heater. Fish tend to become more stressed in these set-ups because they are very difficult to keep stable. Dangerous toxins like ammonia build quickly and require more frequent water changes. In many cases, very frequent water changes will then lead to greater fluctuations in pH. Add large temperature fluctuations from day to night and and it can be very easy for a Betta to become stressed and become susceptible to diseases. Because of this it can be a little more challenging to keep Bettas in a bowl rather than a filtered/heated tank like you would with other tropical fish.

Curing your Betta’s fin rot is a two-part process. First, you need to determine the cause. It may be that 50% water changes weekly and 100% water changes biweekly just aren’t enough. The only way to know for sure is to regularly test for ammonia. Any ammonia, even small quantities, can be dangerous to your Betta and in water with a pH higher than 7.0 ammonia becomes even more toxic. I’d recommend getting an ammonia and pH test kit for your Betta bowl. He may also benefit from 100% water changes weekly instead of 50%.

Treatment for fin-rot varies. Mild cases of fin rot may clear up on their own just by fixing the cause. Once the bacteria has died the Bettafix can help to heal bloody fin tips and regenerate new tissue. Bettafix on it’s own, however, is too mild to treat more severe fin rot. Although they claim to treat bacteria, it is really more of an antiseptic then an antibiotic. For severe cases I suggest dosing with an aquarium antibiotic made to treat gram-negative bacterial infections like Minicycline or Tetracycline. (Mardel’s Maracyn-Two or Maracyn-TC are examples). Fortunately, there are lots of great websites that will deliver your aquarium medications to you so you don’t have to worry about not having a car. (I also don’t have a car) I really like Doctor’s Foster & Smith or even PetCo or PetsMart may provide mail-order fish medications. You can also pick up your water test kits online. The one set-back you will find is that most of these antibiotics are in pill form and designed to treat 10 gallon aquariums. You may have a difficult time dosing for such a tiny bowl. This may be a good time to consider new digs for your Betta. I frequently find 5 1/2 gallon tanks on or at garage sales for free or just a few bucks. Even brand new they are super cheap. This will provide a more stable environment for your Betta, will be easier to medicate and ultimately will be less work for you because the maintenance will be less. Five gallons are also large enough to house a small filter and 25 watt aquarium heater. Creating a complete ecosystem will benefit both you and your fish.

Image of reader’s fish provided by SU.

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Reader Interactions


  1. SU says:

    Is it normal for his tail with the red ends to lighten up which seem to be getting better but still fall off? His tail seemed to be improving greatly but then this happened. Is it normal?

  2. Christie says:

    I’m not 100% sure I know what you mean? Do you mean to lighten up in color? Well, new fin growth, which is a light, often almost clear color, is very fragile and will often become reinfected and fall off. In fact, fin rot, though hardly fatal, can take a long time to heal because the new growth is so susceptible to relapse. It’s not uncommon for fin rot to take several months to heal, and in most fish, it will never grow back the same as it was. You may notice discolorations or what we call “curling” when the fins tips literally have little curly ends to them. Clean warm water is the key.

  3. Christie says:

    P.S. Fin rot is probably the most aggrivating of all common Betta diseases because relapses occur so often and the whole healing part is so drawn out. Just know, when you’re about to pull your hair out, that hundreds… no thousands of others have gone through this battle before you. Myself included. Hang in there. 🙂

  4. Dawn Hawkes says:

    One of my bettas has a very aggressive case of fin rot. In two days he went from full plummage, to splitting, and to deterioration of his caudal fin. He still has PART of it, but it looks almost as if something bigger than him took a bite out of his tail. Due to the aggressive nature of the fin rot, I jumped right to the Maracyn. I’ve had fin rot problems before, but normally a water change and some melafix has helped, but I’ve never seen anything so aggressive before. My question is this… other than the Maracyn, the bigger tank with the heater and filtration, is there anything ELSE I can do to help him get cured?
    He is currently in a ‘hospital tank’. 15 gallons, very little gravel (only what was in his bowl when I moved him) with a heater set at 82 F and a sponge filter. I have splitters in the tank because he is not the only one suffering from fin rot, so I’m treating another one who is not having quite such an aggressive case.
    Please… HELP?

  5. Anonymous says:

    I think my betta fish has fin rot. If he does then t is a VERY early ste. His fins are starting to become like a crowntail. He is also havin some color change. He was yellow/white when bouht him and now his dorsal fin,caudal fin, and anal fin are becomein blue. Is there any way i can fully know if he hasfin rot??

  6. Anonymous says:

    Hello, I think my work betta may have the same issue as Dawn Hawkes’ fish. My betta seemed fine last week, however I noticed maybe a little more inactive then usual.
    But I came back after the weekend and his whole dorsal fin was missing and just the bone sticking out. 🙁
    It seemed as if it had been ripped off as a found a chunk of it floating in the water! I’ve also noticed he developed a grey patch on his back where the fins are missing, and now I’ve noticed another grey patch forming on his head which appears to be turning red.
    Unfortunately I think his water quality had deteriorated, as I was out of the office for a couple extra days. I have since done a full clean of the tank to improve the water quality, but I’m not sure where to start with medication.
    He is currently in a 2 gallon tank with fake plants, and receives a 75% water change twice a week. I use Betta basics for a de-chlorinator to make sure his PH balance is always constant, and I’ve been keeping the water at a constant 80F.

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