Betta fin rot that won't heal after medication

You've dosed a full course of medication and the fins look the same or worse. That's frustrating, and it's common. It usually means the cause is still there.

Fin rot is almost always a water problem first. The bacteria behind it live in every tank. They only get a foothold when the fish is stressed, and the most common stress is water quality. Medication treats the infection, not the reason it started.

Start here

1. Test ammonia, nitrite and nitrate. Anything above zero ammonia or nitrite, or nitrate climbing past about 20 ppm, needs fixing before anything else will work. Our Water Check turns your test results into a plain-English fix.
2. Check the temperature. Bettas do best around 78-80 °F. A cold betta heals slowly.
3. Look at the decor. Rough edges and plastic plants can tear long fins, and torn fins get infected.
4. Rule out fin biting. Some bettas chew their own tails when bored or stressed. Bitten fins look chunked and uneven with clean edges, and don't spread to the body.

Then, while it heals

• Small, regular water changes: 20-30% weekly in a 10 gallon, more often in smaller tanks.
• Clean, warm, stable water. That alone heals mild fin rot.
• Only if the rot is still spreading toward the body after a week of good water, treat with an antibacterial and finish the full course.
• Indian almond leaves are fine but won't fix the cause.

How to tell it's working: new growth comes in as a thin clear edge along the damaged fin. It can take weeks to fill in, and it may grow back a slightly different shape or color. That's normal.

More on the signs: fin rot. Care basics: betta care guide.