Fin Rot Information and Symptoms
By Rachel Hunt (Mushi)
Fin Rot is arguably the number one issue you will have
to deal with if you keep any number of bettas for any length of time. Fin
Rot is a bacterial infection of the fins, usually brought about by poor
water conditions and/or stress that causes the fins to deteriorate. Fin
Rot can also set in when a fin is injured and the water is not kept clean
enough to avoid infection of the injured fin.
A Betta with Finrot © Mushi
Small holes (pinholes) anywhere on the fins.
that seem to be growing thinner or more transparent.
Fins that seem
to be "fraying" around the edges.
Fins that seem to be breaking off
in large chunks.
Slimey looking areas, usually on the tips of fins,
that seem to "eat away" at the fins over time.
Fin Rot in and of
itself is not contagious, but if you keep fish in a community tank you may
end up with several fish contracting the infection. This is because the
bacteria that cause Fin Rot are opportunistic bacteria - poor water
conditions stress fish out, and when fish become stressed, their immune
systems become weak. Weak fish are not able to fight off illnesses that
healthy fish easily can. So if you have poor water conditions or something
else causing stress in the occupants of your tank, you may have an
"outbreak" of Fin Rot.
Quick Medication Dosing Tip
medication dosing directions are meant for larger tanks and some
medications come in tablet or capsule form, it can be difficult to
dose a small container. There is a trick to doing this.
your medication calls for one capsule to 10 gallons, grab a small
container that can hold water. Using a measuring spoon, measure out
10 teaspoons or tablespoons full of water into the container (it
doesn't matter which you use as long as you use the same unit of
measurement the whole way through). Dump the capsule or crush the
tablet into the measured water. Then dispense the medicated water
into your isolation container - if it is a 1 gallon container, one
teaspoon/tablespoon will be the correct medication dosage. This
method works for any size treatment container, just be aware that
most medications lose effectiveness after 24 hours in water so you
will have to discard any unused medication using this
Fin Rot Treatment
Fin Rot is not contagious, it is still a good idea to isolate a betta that
you are attempting to treat for Fin Rot. There are several reasons for
this, but the main reason is that it's much easier to keep the water
absolutely pristine when you have a fish in an isolation container. The
secondary big reason (maybe this should be first) is that many medications
used to treat fin rot can kill your biological filtration, live plants,
and may be harmful to other animals in your tank (depending on the
medication and the other animals). It's also just generally a good idea to
isolate any sick fish when treating them so that they are not getting
picked on and there is no chance of passing any secondary infections on to
other fish, as well as making it easier on you to monitor the health and
progress of your fish.
Enough of the "isolate your sick fish"
lecture (you're probably sick of it by now if you've been through other
parts of this site, right?). Fin Rot is caused by gram-negative rod
bacteria. Fin Rot can be easy to treat if you catch it early enough and
maintain your water quality pretty well, or it can be a complete pain in
the bottom if you don't catch it early enough or allow your water
conditions to fluctuate over long periods of time (you know, we all get
lazy every once in awhile).
If you catch your Fin Rot in the
"pinhole" or "just starting to fray" stages, you may have good luck
getting rid of it by simply increasing the number of water changes you do.
If your betta is in a small, unfiltered tank, simply doing daily 100%
water changes for a week may reverse the beginning stages of the illness.
Adding 1tsp of aquarium/rock salt per gallon of water to the isolation
tank along with doing daily water changes may also help take care of these
bacteria in the very early stages.
Important Medication Note
If you notice that the
Fin Rot is getting worse or is way past this stage when you notice it,
it's time to bring out the big guns. Because Fin Rot is a gram-negative
rod bacterial infection, you want to treat it with either a good, broad
spectrum antibiotic or an antibiotic that specifically treats
gram-negative rod bacteria. My favorite medications to treat fin rot are
Fungus Eliminator and Tetracycline. If you are unable to find either
of these medications, other options are Maracyn II (you can use it in
combination with Maracyn if you want to cover all the bases) and Kanacyn.
Simply follow the dosing directions on the medication, keeping in mind
that since you are treating in a small container you will have to do full
water changes and add new medication instead of doing the partial changes
many medications specify.
will try to sell you a product called Melafix or Bettafix for the
treatment of Fin Rot. In my personal experience, neither of these
products (which actually have the same active ingredient, Melaleuca
or Tea Tree Oil) will help with the treatment of true Fin Rot. They
may help regrow fins damaged by Fin Rot once the bacteria is killed
off, but they are not the right type of medication to actually
"cure" Fin Rot. Treating with either of these products may stop the
advance of the rot, but once you stop treatment it is almost
guaranteed to come back. Don't be fooled into purchasing this
medication as treatment for Fin Rot, although you can purchase it to
use after you've cured the rot and just want something to prevent
growing fins from being re-infected. End of lecture!
personally like to continue treating with Fin Rot medications until I see
good, solid fin regrowth (about 1/8"), even If that means I treat longer
than the treatment schedule calls for. I do this because many times
medications will stop the progression of the bacteria, but may not kill
them all right away. If you stop treatment before all of the bacteria are
killed off, odds are the Fin Rot will return as soon as you stop
medication. Fin regrowth is an excellent sign that the bacteria have been
taken care of.
If you run through 3 treatment cycles (usually about
15 days for most medications), you have kept up with the water changes,
and do not see any improvement in the condition of the fins, you may want
to switch to another medication. Before switching medications, give the
betta a "med vacation" of about a week, changing his water (without adding
any medicines) every day during that week before starting a new
Sometimes you will get a stubborn case of fin rot that
nothing seems to help, or a betta that just seems prone to contracting Fin
Rot over and over no matter what you do. If you run through several
medications and nothing seems to help, you may want to just try
1tsp/gallon of rock/aquarium salt and daily water changes for a few weeks
and see how he does. Sometimes we can so overmedicate our fish that the
medications themselves start stressing them to the point they get sicker
and sicker and stopping medications might be the most humane thing we can
do. I've had extremely Fin Rot prone bettas do excellently with just daily
water changes after all else had failed.
Because Fin Rot is an opportunistic disease, keeping
your betta in optimal conditions will greatly reduce the chances of him
getting Fin Rot.
Always keep a betta's water so clean you could drink
it (not that you'd want to, but...).
Always keep bettas at a good,
steady temperature. Fluctuating temperatures or temperatures that are too
cold (under 72 degrees F for long periods of time) or too warm (above 82
degrees F for long periods of time) can greatly increase the chances of a
betta getting ill.
Feed a well-balanced diet to avoid nutritional
deficiencies that can weaken the betta's immune system.
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