My Betta Fish's Tail Looks Like It's Decaying?


He's in a 2.6 Fluval Tank with filter and lights. Temperature is at a constant 76 degrees. More info about the tank:

- Waited 1.5 months for tank to cycle and did a 80% water change before I acclimated him.
- Amazonia Substrate
- Driftwood
- Carpet plants (growing faster than the swords and java fern I put in there)
- Large Rock (to keep driftwood from floating)
- Tank gets 4 hours of light a day (had to cut back from usual 6 hours because I have a huge green hair algae and still struggling to control it now)

Tank Parameters (used API Test Kit for Ammonia, Nitrite, Nitrate, and PH. Used a strip to get a GH/KH reading):
Ammonia - 0
Nitrite - 0
Nitrate - 5
PH - 7 - 7.2
GH - 30
KH - 40

Yesterday I noticed that my bettas tail fin was shredded. I don't know if he was chasing some floating algae in the tank thinking that its food but it had black/gray tips on it so I thought it was fin rot. Thing is, the water parameters seemed fine. I tested the water multiple times so I don't know what's wrong. I checked it back the next day and it healed up a bit, but when I dropped some food and he chased after it. When he jumped, I saw pieces of his "recovered" tail falling off! Now it looks even worse than before! The flow isn't strong ( I put a sponge on filter). He's acting like he's usual self, but his fins look really "thin." I don't know what's causing this

His previous home was a 1/2 gallon container with a heater. I did 50% water changes everyday and every 3rd day, a complete water change. I never saw him have any fin rot when he lived in that container. I'm surprised when I moved him into a bigger home, his tail fin is falling off. It's just the edge but still, I don't like seeing him hurt.

Other than the hair algae problem, could something in the tank be damaging his fins? He's the kind of betta that likes to squeeze himself into the carpet and snake his way through the leaves.. could it have gotten caught? The reason I cycled the tank was that I don't have to do water changes everyday, just every 7 days. But now.. I don't know what to do. Can someone help me please? I had him since he was a baby and it pains me to see him damaged like this.


There may be something sharp in the tank. I would also consider rehoming as 2.6 gallons is too small for a betta.


Hey. It’s hard when something is wrong. Let’s see what’s going on. Hopefully discus-tang is right and it’s decor. Could you please post pics? And if you can, go ahead and get a five gallon tank. But right now we’ll try to help you figure this out.


A 2.6 gallon fluval is fine for a single Betta Fish. Usually fin rot is caused by poor water quality, so if it’s not that, it may be tank decor. Plastic plants, sharp pieces of plastic decor, and rough driftwood could all be the culprit.

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