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Fin Rot
Our bettas' long flowing fins may be the thing we love most about them. To see them being eaten
by fungus - sometimes at a frightening rate - is pretty upsetting, if not truly traumatic. Here's
what to do right now to stop the damage, and how to prevent it going forward.
Symptoms of Fin Rot
There are different kinds of fin rot, but they all take the same treatment. Here's what to look for:
white tips on the edge of fins
fins starting to dissolve from the edges... it looks a bit like dried
paint that's been exposed to paint thinner
holes in fins, or fins starting to appear thinner than usual
symptoms may develop quickly, or slowly progress over a few days.
the fins make start to look stiff
slimy areas near the top of the fins that seem to eat away at the fins over time
What Causes Fin Rot?
Short answer: gram-negative rod bacteria that take advantage of a weakened immune system when a fish is stressed.
95% of the time, the stressor is dirty water.
Much longer answer: If your water is perfect (recently changed, between 76-80 degrees, with pH between 6.8 and 7, treated
with a good water conditioner and just tested to be completely clear of any ammonia or nitrates), then
look to other stressors. Is your tank overcrowded? Are you feeding new food, or food that may have gone
bad? Has there been an extreme temperature drop? Borderline water and any one of these events can
trigger an outbreak.
Fin rot starts as fin burn, which is caused by dirty water. The ammonia and other
bacteria in dirty water wear away at your betta's natural slime coat, and over time
stress your fish pretty severely. This can go on unnoticed for months. If the fish has a
sudden shock like a change in water temperature, jumping out of its bowl (even if its rescued quickly),
or anything else, that can suddenly make the previously invisible condition visible.
Your betta's fins are only a few cells thick,
so they're the first parts of the fish to show the damage.
Keep in mind that "dirty"
water may not look dirty to you - your bettas waste and uneaten food will sink to the
bottom and get loaded between the bits of gravel. Down there, it slowly decays and releases
the poisonous ammonia that pervades the whole tank. Always stir up the gravel when you're doing a
water change or you really won't be making much of a difference to your fish.
Even if you have a filter, all those
wastes will still break down into ammonia, and if you don't do a 80% water change as often as you should
(every 5 days for a 1 gallon tank, every 7 days for a 2 gallon tank, every 10 days for a 5 gallon tank),
then your fish is going to get sick. Its a little gross, but here's the best way to really be honest
with yourself about how clean your betta's water is: would you drink it? If you just made a face,
then its time to do a water change.
Actually, if your fish is showing signs of fin rot, they've almost certainly also got gill burn
or even gill rot. This is the equivantalent of lung burn or long rot to us. Its bad news.
Continue to What to do About Fin Rot?
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