Persistent Fin Rot - need help, please!

[Joli Bean]

Hello, and thank you for sharing such a wealth of information with all of us.

We have a Betta that we bought at the pet store ~1 year ago. He lived in a 5 gallon tank until recently when we upgraded to a 26 gallon aquarium. Several months ago, Jax got fin rot, which we originally treated with Maracyn 2. It improved, but he never regained the full length and size of his fins, and has continued to struggle with fin rot ever since.

About 3 months ago we got a more accurate water test kit and realized that we have quite the fluctuating pH situation going on. It will start out around 6.8-7.0, then within a few days it drops to 6.2-6.4. We have tried all kinds of things like pH Up, pH 7.0 (in moderation - we know that trying to correct the pH with too many chemicals can harm the fish.) We've added several coral rocks, and still the pH drops alarmingly. (Wondering if the acidic pH is burning his fins or if it is truly fin rot? He is red, and the edges of his fins have never looked black or white as some descriptions of fin rot say, but it sounds like fin rot based on the shrinking and shredding of his fins).

The fin rot recently (1 month ago - shortly after moving to the 26 gallon tank) got much worse - his tail is shredded and split, we tried a few rounds of Maracyn again, and Bettafix (which I then read not to use - so confusing - everyone has different advice). We were advised by a pet store employee to try an antifungal and an antibacterial, so we just completed a 10-day treatment of API Pimafix and API Melafix. It does not seem to have helped at all.

We are at somewhat of a loss as to what to do, it feels like we have tried everything and we love this little fish and don't want him to suffer. Thank you for any tips and/or advice.

I'm enclosing before and after pictures for a comparison. (the lights in the tanks and in the room are different, so it makes his color appear very different)

Housing
What size is your tank? 26 Gallons
What temperature is your tank? 79-80
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? Air stone
Is your tank heated? Yes
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Pellets (Aqueon Beta Food)
How often do you feed your betta fish? Daily (4-6 pellets)

Maintenance
How often do you perform a water change? Weekly
What percentage of the water do you change when you perform a water change? 25%
What type of additives do you add to the water when you perform a water change? Stress coat, Aquarium salt, Top Fin Bacteria supplement, AmQuel Plus Ammonia Detoxifier, pH 7.0

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia: 0 (though we had a recent spike after the antibacterial and antifungal treatments, so just did a full water change and it is back to 0)
Nitrite:
Nitrate:
pH: 6.6
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed? His color is a bit less vibrant, fins are shredded and shortened
How has your betta fish's behavior changed? He's less active but still an eager eater!
When did you start noticing the symptoms? Originally ~6 months ago, it has been off and on since then.
Have you started treating your fish? If so, how? Have treated several times with various treatments, none of which seem to help permanently (Maracyn 2, Bettafix, Pimafix, Melafix - see above for history).
Does your fish have any history of being ill? Only with the fin rot
How old is your fish (approximately)? 1 year?

[callistra]

Antibiotics will toast your cycle and require you to start all over.. meaning daily tests for ammonia and nitrite and doing 50% change any time you see either show up. Could take up to a month or so again to get it back under control.

Using chemicals to alter ph are not a good plan. The swings are very hard on fish and can even be lethal is the swing is too wide or too fast. What is the source of the water you are using? Tap or?

Also the lowering of ph can be an indication of ammonia.

Is there anything sharp in the tank that could snag his fins? Do you have the filter prefiltered? Have you used panty hose to test all ornaments and fake plants to see if they snag?

I would QT by getting a 2-3 gallon kritter keepter, filling it half full and then floating it in the main tank for warmth. In this I would do daily 100% water changes along with the redosing of meds for up to two weeks or until you see no more signs of fin rot and you actually see some regrowth. I would look for Kanaplex by Seachem, Maracyn Plus, Triple Sulfa or Furan 2.

[Oldfishlady]

With the low pH-you will have a hard time getting the beneficial bacteria for the nitrogen cycle to colonize to start with. However, one good thing about the low pH is that any ammonia will be less harmful ammonium. I suspect you have soft water or low GH/KH and any products you add will not help much until you get that stable.
How much crushed coral did you add to the tank

Tell us about your source water-is it well water, city supplied tap water...etc...Do you have a water softening unit hooked up to the house, if so, can you bypass this to use for the aquarium if it is the kind that uses salt.

With some Long fin male Betta-space and water movement can be the cause of fin damage. These delicate long fins can tatter due to using them to swim in general in large space-especially with water movement.

You want to be careful over medicating due to toxic reason and this can compromise the immune response-as well as mask S/S.