The Root of Fin Rot and How to Stop it

Do you think your fish has fin rot?  Don’t fret.  Fin rot is a very common fish disease.  The good is that it is treatable and preventable.  The bad is that it can kill your fish if you don’t act fast.  Fin rot is caused by bacteria.  The most important thing to take from this is that fin rot strikes fish when they are stressed.  Fix the problem that is stressing your fish and you can quickly treat and deal with the problem.

Let’s Make Sure it’s Fin Rot

Fin rot can spread to the body of your fish in its later stages, but it starts with the fins.  Don’t forget it’s bacteria which means it can quickly spread.  Rotted or ragged looking fins, white edges on fins, or puffy sores on the fins, are all signs of fin rot.  In the later stages of fin rot you might also notice a lose of appetite.

So Why Does My Fish Have Fin Rot

The number one reason for fin rot is stress on your fish.  This is just about always caused by poor water quality.  Clean up your water quality first and foremost.  Secondly, you must develop some good fish tank care habits.  Regular water changes and weekly water testing are essential to maintaining a healthy fish tank.

4 Things to Do Before Treating Fin Rot

  1. Regular Water Changes
    • This is probably the most important step.
  2. Testing Often
    • Test your tank water weekly to correct any known problems fast.
  3. Get Rid Of The Bullies
    • Bullies can nip at your fish’s fins leaving them susceptible to the fin rot bacteria.
  4. Feed With Care
    • Be careful not to overfeed your fish.  Left over food will quickly lead to lead to harmful water.

Then What?

Tetracycline is the most popular way to medicate your fish with fin rot.  There are other antibiotics that will also work well.  You can find them at your aquarium retailer.  Just follow the directions on the bottle.  Make sure to first correct any of the problems above first.  If you don’t address the root of the problem medications will have a tough time keeping up.  The last you want to do is over medicate.  That’s it.  You are now on your way to a fin rot free tank.

What’s your experience with Fin Rot?

, , ,

23 Responses to The Root of Fin Rot and How to Stop it

  1. Mary January 6, 2008 at 7:15 am #

    Hi. Just when I thought everything was going great w/ my new fish. I get another disease. My redtail shark has some fungus that looks like fuzz on her. I think I’m going to buy Maroxy for her. Can she spread this on to my other fish? I sure do hope not.

  2. Eric January 9, 2008 at 9:24 pm #

    Hey Mary, Sounds like you have a fungus of some sort. From you description, it could be Saprolegnia. This fungus has a spiky type fuzzy look to it. The Maroxy is a good treatment option. Maroxy can be used to treat both fungal and bacterial diseases. Most fungi can spread, so I’d quarantine if you can. Good luck!

  3. Nath January 22, 2008 at 12:49 pm #

    My son has just had fish for a couple of weeks. Only 6 two of each type. One died yesterday and now it’s partner has developed what initially looked like an injury to it’s side but this has now gone very white. Wwe thought initially it was an injury, now I am not so sure… anyone able to offer any advice?

  4. Eric January 24, 2008 at 7:24 am #

    Hi Nath, Sounds like your fish probably has a fungus of some sort. This might look sort of cotton like. There over the counter medications to treat all sorts of fungi.

  5. Sally February 19, 2008 at 2:17 am #

    We’ve had four of our fish die in the last month. Now our four inch goldfish has white stringy stuff on his gills, eyeballs, and what looks like translucent fins. One of the cave dwellers is struggling with what looks like a curved spine, and our upside down catfish is staying afloat on the top of the tank listlessly with the odd movement here and there. Now are flying foxes are starting to swim above the aquarium’s decorations which they never used to before. They are usually well hidden and like to play around the bottom of the tank.

    We’re not sure what’s going on.

  6. Eric February 21, 2008 at 7:18 am #

    Hi Sally,

    The white stringy stuff could be any number of things. Columnaris, a bacterial disease comes to mind. Might be a fungus of some sort.

    The curved spines leads me towards Swim Bladder disease. This is usually caused by eating too much, too fast. The swim bladder being out of whack causes the mid section to floaat towards the top of the tank. This makes the spine looks curved.

    Swim Bladder treatement would be to cut back feeding for a day or so. You can also try feeding shelled peas. This helps clean them out if they will eat them.

  7. Kyle February 24, 2008 at 12:14 am #

    My fish has white fussy bumps on his back tail and he keeps on having sisers or jerking movements. Also hes a goldfish and his ph is 6 does that mater. And how do i remove carbon from my filter because i got this thing for ick treatment but i dont know if he has ick it also cures external parasites. And his anal fin no looks like its been riped and he flairs it out with all his other ones and flys around the tank like somethings after him. Please help. Also he lives in a 10 gallon tank and hes 5 inches long and like 2 inches tall when his fins are normal. Could it be this fin rot stuff? Can I put the fin rot medicine and the ick medicine in at the same thim or would that be bad or even faital. Tomorrow is his 5th birthday (25th of September to 25th of Feburary) and i want him to live at least a year more than that would be awsome. After this should i get him a new friend to help him with stress? If thers any other questions you have for me about the set up of his tank or him just ask. PLEASE HELP MY FISH!!! thank-you

  8. Eric February 24, 2008 at 3:15 pm #

    It does sound like Ich. Not sure on the Fin Rot. Most of the Ich medications do also treat many external parasites. I would treat the Fin Rot separately with an antibiotic if you come to the conclusion that is what you are dealing with.

  9. Kyle February 24, 2008 at 8:57 pm #

    thank you eric now how do i get carbon out of my filter to treat the ich.

  10. Eric February 29, 2008 at 3:32 pm #

    You’re welcome Kyle! It sounds like you have a sealed filter that has the filter and carbon together. Maybe an Eclipse? Just cut a slit in the filter part and pour out the carbon if this is what you have. After treatment you can just replace the filter with new.

  11. bethan southcott March 27, 2008 at 8:58 am #

    my angel has a bab case of fin rot iv treated him im just want to know will his fins grow bk ? thanks beth

  12. Eric March 30, 2008 at 8:08 pm #

    Hi there Bethan,
    Many times fins will grow back. You’ll have to get the fin rot completely cleared up first. With good water conditions you have a great shot at it.

  13. Leslie June 18, 2008 at 2:34 pm #

    One of my mollies has something wrong with his tail fin. He’s seems healthy, but his tail fin floats! It’s possible for him to swim to the bottom but if he just sits there his tail drags him up. I don’t know what’s wrong and I don’t know how to help him. I’m worried because his back is getting bent upwards and it might be damaging something inside him somewhere. He also might be in pain. 🙁
    whats wrong with him and how can I help him??

  14. Eric June 23, 2008 at 6:11 am #

    Sounds like Dropsy.

  15. MJ July 15, 2008 at 9:13 am #

    I’ve had a 55 gallon tank for about 10 years now with mostly angelfish, some corey cats, a pleco, and some neons. Of course my fish have passed on here or there but I’ve never had any real problems, until 3 days ago. I noticed some of the angels weren’t eating and were acting a bit strange, and my catfish & pleco which normally hide out in the dark were swimming all about. The pleco actually started swimming very fast from the bottom of the tank to the top and was coming through the surface of the water and banging the cover of the tank (he was about 6 inches). It went on all day like that but I couldn’t see what was wrong with them, no outward signs of disease and not swollen like dropsy. I tested the water and it was fine but I changed 25% of it anyway. And I have a water ionizer with pH selection so I know the water I put in wouldn’t stress the fish out more. Anyway, when I got home from work that night 2 of the angels were dead, they were originally black but their bodies were all white and not fuzzy, it looked like the scales had changed color. Obviously I knew something was wrong but didn’t know what. I had bought a live plant from a store about 7-10 days prior to this so I thought maybe the disease could’ve come from the plant? Also, I never had snails in my tank before and all of a sudden I have about 500 baby snails EVERYWHERE. I’m assuming they were somewhere on the plant and that’s how they migrated to my tank. Seriously, the rate at which these snails are reproducing is ridiculous, they’re beginning to clog my filter and cover almost every surface. The snail ‘outbreak’ seemed to start on the day my fish started acting strangely so I was wondering if anyone had ever heard of something like that affecting fish? Sad to say but as of last night every single one of my fish has died. I have nothing but a tank full of snails! How long should I wait to make sure that my water isn’t contaminated before getting some new fish. I can’t stand to look at the empty tank when only days ago I had 7 big beautiful angelfish in there!! Thanks in advance for any advice you can offer.

  16. Eric July 17, 2008 at 8:32 pm #

    Hello MJ,
    Sorry to hear about your Angels. Snails are also a pain, especially in those numbers. Given you experience, I usually wouldn’t lean towards the basics but these are the most common reasons for your problems. I’m sure you did get your snail from new plants. This is VERY common. They multiply very rapidly under the right conditions. Excess nutrients from overfeeding or excess waste are usually the cause. I would only think this could be the case if you have changed habits recently. Excess waste could also explain fish lose by high levels but that should have shown up with testing.

  17. MJ July 21, 2008 at 9:24 am #

    Thanks Eric, I think you’re definitely right. I had recently moved the tank and done a complete overhaul so I thought it was in good shape but my husband has a tendency to feed the fish WAY too much and after I have already fed them. I tried to tell him not to but he says he feels bad because they look hungry 🙂 He’s never had fish before. And I also bought my plant from Petco, which I NEVER do since I have always had some type of disease infect my tank after buying any fish there. But I thought a plant might be safe. Not so much as it turns out I guess!! Ah well, such is life. I’m moving soon so I suppose it is just as well since I can now break down the tank completely and restart at my new house. Thanks again!!

  18. Eric July 22, 2008 at 6:29 am #

    Your welcome MJ! Overfeeding is such a common problem for the same reasons your husband had 🙂 Good luck with the new setup!

  19. Brent July 23, 2008 at 9:05 pm #

    I have one large oscar and two smaller ones…. The larger one had a slight tear in a fin about a week ago and I noticed another today. the tips of his top and tail fins are white, but they are also so on one of the smaller ones. (both these two are the same color scheme)

    Do you think it could be fin rot or are both the tiger oscars supposed to have white tipped fins? Also, it may be possible the torn fin is from occasional fighting right?

    I keep up on the aquarium’s maintenance and test the water quality regularly. I don’t want to medicate if its not neccesary. What else should I do / look for?


  20. Eric July 28, 2008 at 5:41 am #

    Tiger Oscars do commonly have a white sort of outline to those fins. The tears could definitely be from some nipping or fighting. As long as it isn’t too bad, I’d keep a close eye on changes or advancement. If it’s getting worse than you might be dealing with fin rot.

  21. Brent July 28, 2008 at 9:32 am #

    Thanks Eric, I appreciate it.

  22. Danielle July 16, 2011 at 11:35 am #

    I have molly fish that I recently treated for fungus. It appears the fungus is gone since there are no more white patches on the fish, but now the top fin on my female molly is gone. It just looks like a spikey/spiny fin and she lays on the bottom of the tank. I put her in the hospital tank, but what could this be?

  23. Eric July 19, 2011 at 6:13 am #

    Hey Danielle – Still sounds like fin rot. Fin rot can actually eat all the way down to the base of the fin it worst cases. If you have it in a hospital tank, I’d keep treating for the bacteria.