Whenever I lurk the #betta fish tags, I see so many posts of people not knowing what to do when their fish gets fin rot. I feel bad and just want to help them out, but sometimes its super hard to effectively get back to them.

So here, this is a tried and true, tested and effective method to get rid of (non-severe) fin rot using Aquarium Salt/ Non-Ioddized salt.
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First thing is: What is rot and how did this happen?
Fin rot is caused by bacteria that is living in your fish tank. All tanks have this bacteria in them, and it is not inherently dangerous. What makes this bacteria dangerous is when the tank is not clean, if it is over stocked, or if the fish is injured or stressed. The bacteria that causes fin rot is gram-negative.
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Important step:
Assess your tank.
Be honest with yourself. Are you cleaning the tank enough, is the water frequently changed for the tank’s size? Is your fish living with tank mates that it shouldn’t be, or living with too many other fish? These issues are critical to relieving fin rot, as the fin rot will not go away unless the tank is kept clean and not over stocked.
Be honest with yourself to save your little fish.
A tank under 2gallons should be changed at least once a week completely.
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How do I know its rot?
Mild(er) cases of fin rot are…
- Mild tattering on the fins to moderate tattering
- Slightly darker in color or turning grey/brown at the tips
- Only present on the tips of the fins, not near the body
- Small amounts of redness at the fin tips/ some irritation
(Big rips do no necessarily mean rot, but its good to be careful the rip stays healthy!)
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FIRST STEP:
Here’s what to do first:
- “Quarantine” your fish if it lives in a tank over two gallons, lives with other fish or snails, or if it lives with live plants.
- If your fish is in a tank larger than two gallons, etc. find another container that is clean and safe to treat the fish in. This allows you to not need to do as large of water changes, spares other fish from being harmed, and saves plants from medicines that may kill them.
- Try to keep the “QT” tank .5 gallons-2 gallons, as it is easier to dose medicines this way.
- Once the fish has a QT home, float it in the original tank to keep the fish warm. You can tape the QT container against the tank. Doing so will prevent the QT from tipping or being knocked around. Take care that if it has a lid with holes that it doesn’t flip over, which will drown the betta. If you are doing this in the main tank and its heated, that’s fine.
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NEXT:
Now that the fish has a temporary home to be treated in, you need to focus on the water:
- Change the water 100% in the QT tank. This helps get rid of or discourage bacterial growth. Be sure to properly acclimate the fish when doing the 100% change in the QT.
- Try and keep the water the QT tank is bobbing in at or around 76-78’F. This range discourages the spread of bacterial growth.
- Keep the lights off in the tank as well as the filter ( if you are treating in-tank), as the current will hinder fin regrowth.
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USING SALT:
- Take a clean cup of some sort to mix clean tank water and salt in. Take a small amount of the QT tank’s water out and into this cup.
- Add in 1 teaspoon per gallon of Aquarium Salt into this cup and allow it to dissolve fully. Stir it around to mix faster. So, if you have 1/2 gallon of water, .5tsp, 1 gallon of water, use 1 tsp of salt, 2 gallons, 2 tsp of salt, and so on. This is why you use a smaller container, its easier!
- Add the salt/water mixture back into the QT tank gently so it wont knock around your fish.
- USE SALT FOR NO MORE THAN 10 DAYS.
Your fish now has all the medicine it needs to cure its fin rot.
- Stay away from unnatural remedies, as these can be dangerous when not dosed correctly. Salt and clean water does wonders. Melafix and bettafix do not cure rot. They are antiseptics.
After one day, do a full, 100% water change in your QT tank.
- This is important because it keeps bacteria growth down, provides a clean environment for the fish, and makes re-dosing the salt easier.
- After a 100% water change (100%!!!), re-dose the 1tsp/gallon of AQ salt.
- Acclimate your fish properly and gently each time you do.
- USE SALT FOR NO MORE THAN 10 DAYS. Try for 5.
DO NOT COMPOUND THE SALT DOSES EACH DAY. Do NOT add 1 tsp one day, 1 tsp the next, etc, while not changing the water. It will kill your fish!
Hope this helps! Be careful when treating. For questions, just ask.
All info here is from my blog here. I address using medicines and antibiotics as well as more severe to very severe rot. Check it out!!