Anhel asked me to take a look at your thread. Is this a pretty good summary of what's going on?
- Originally in a 2.4L tank with a heater.
- You moved him into a new 12L tank with a new filter (baffled) and a new 25W heater.
- You're in Australia. (Knowing this gives us an idea of what products you can/can't get.
- You're using Betta Shield water conditioner. (Removes/neutralizes ammonia, chlorine and chloramine. Contains aloe vera and colloids.)
- His fins are clamped and "stringy." Eating well (until yesterday).
- Water temp about 26C.
- Did not eat his usual pellets.
- "Barely moved" and is hiding.
- pH at 7.6
- Ammonia at 0.50 ppm.
- Tap water tested positive for ammonia. (Possibly about 0.25ppm?)
- His fins are having problems, and you feel it's fin rot.
Your pH is fine. I would not try to change it.
The ammonia level is high, however. I'm thinking the high ammonia level is due to the tank not being cycled yet. I would increase the frequency of water changes, and keep using Betta Shield, as these are the best ways to keep ammonia low/neutralized.
I have some questions:
- What is "new" in the new 12L tank? (I see gravel, decorations, heater, plants, filter. Are these "new?" What about anything else?)
- What was the water temperature in his old tank? Is it different from what's in his new tank?
- How long after switching him to the new tank did he display symptoms? Did he seem OK at first? (And for how long was he OK?)
As been suggested, you may want to get a glass thermometer that goes inside the tank. They're more accurate than the stick-on types.
I'm wondering if there's something new that was added to the new tank that's causing an issue.....
Can you try an experiment?
- Note the temperature of the water. (Use your thermometer.)
- Using a plastic cup, scoop him, along with some of his water, into the cup.
- Rinse out the tank.
- Put only the new heater and thermometer back into the tank. (Nothing else yet. No gravel, decorations, plants, etc.)
- Refill the tank with water at the SAME temp. (Within +/- 2 degrees F, or 1 degree C.)
- Be sure to add the correct amount of water conditioner.
- Float his cup in the tank for about 15 min. (Longer is OK.)
- Add a SMALL amount of NEW water to the cup. (Several tablespoons, or about 1.5 ounces.)
- Let his cup float for about 10 min. (Longer is OK.)
- Repeat the above two steps, until about an hour has passed. (Longer is OK.)
- If the cup starts to fill too much, remove a SMALL amount of water from the cup. Discard it.
- Gently release him into the tank.
You said that it looks like he has fin rot. Can you describe what the tips of his fins look like? Are they dark (black, brown or gray)? Do the edges look "smudged" at all? These are signs of fin rot.
Can you post a new photo of him so that we can see what he looks like today?