Jagged Betta Fin?

Hi all, I'm new to this fish forum and I registered because my male betta (blueberry) has a jagged back fin. It happened pretty suddenly and not a lot of his fin is gone though it seems almost like a triangle at the points where it was ripped. I have a sponge filter, sand, silk plants, and he's living in a split 10 gallon with my female betta, Pearl. (Basically he has 5 gallons of space and there's a barrier separating them). Blueberry used to live in a small 1-gallon tank with no filtration or heating at all but I upgraded his situation. His fins haven't been in top shape ever since but they've healed quite a bit. I feed him bloodworms and Hikari Betta Bio-Gold.

Here is some photos: I also forgot to mention that he also has a bit of black fin as you can see in the photo (was always there though, unlike the jagged part).


So, what do you think? Is it fin rot? A teared fin? Tail biting? And how do I treat it? Yesterday I applied some API stress coat into the water and it didn't seem to get worse (at least I didn't notice yet).
Thank you for your replies.

Welcome to the forum!

Do you happen to have any photos before the jagged edges/tears?

(Also, will you please include a photo of the whole Betta?)

Sorry I uploaded that on my hamster channel.
I just noticed that his fin was already torn (worse) before. I'm not sure if it was already torn but one day I just noticed it all of a sudden.
This video is from a couple of months ago so I don't know. Also, is it even torn? Or is it just the fin's outline? I'm new to bettas.
Thank you!

Welcome to the forum.
Is the tank cycled? What are your readings for ammonia, nitrIte, and nitrAte?

TBH, I'm not a fan of these "split" tanks, when the male can see the female...can cause unnecessary stress

Hi, thank you for the reply.
I did not know much about cycling tanks back then and I thought the big tank would be better than the small one since the small one got dirtier.
I used to have a test kit but I think it got thrown out. I'm not sure about the ammonia/nitrite/nitrate levels since, as I said before- I think it got thrown out.
My female betta seems to be doing fine, her fins are looking very healthy. There are algae in the sponge filter IDK if that means there's some kind of bacteria growth.

Common cause of jagged fins/fin rot in fish is poor water quality.

Get one of these ASAP: https://www.amazon.com/dp/B000255NCI/?tag=ff0d01-20

And a bottle of this: https://www.amazon.com/dp/B00025694O/?tag=ff0d01-20

Test your water, and post the results here

Hi there! So I got between 0.5-1 ammonia, 0-20 nitrate, and 0 nitrites. Could it be the ammonia causing the problems? Otherwise, I think the nitrite and nitrates are at a safe level. (if I'm correct)

P&BtheBetta said:

This video is from a couple of months ago so I don't know

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Welcome to the forum Did you notice on your video your filter pulling your betta tail against it anything like that can harm them, i've got a top filter on mine and the pump tube is covered with mesh to stop this.

Tez_20 said:

Welcome to the forum Did you notice on your video your filter pulling your betta tail against it anything like that can harm them, i've got a top filter on mine and the pump tube is covered with mesh to stop this.

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No, I don't think so. I have a sponge filter and I even put it on the other side afterward. The flow isn't that strong and he doesn't go near it that much. I don't know if it was the previous water conditions that he lived in that caused this? Do you have any tips for growing the fins back? Thank you!

BTW it might be healing a bit unless I'm seeing things incorrectly... he seems to be active as usual and likes swimming in his tank.

P&BtheBetta said:

No, I don't think so. I have a sponge filter and I even put it on the other side afterward. The flow isn't that strong and he doesn't go near it that much. I don't know if it was the previous water conditions that he lived in that caused this? Do you have any tips for growing the fins back? Thank you!

BTW it might be healing a bit unless I'm seeing things incorrectly... he seems to be active as usual and likes swimming in his tank.

Click to expand...

Although I've never had this myself, you need to make sure your tank is spotless for Betta fish as any bacteria can latch on to them.
Do a 30% water change, make sure your readings are fine, clean your glass & vacuum, then get some aquarium salt & add the amount it suggests to your water. All this is essential for an healthy Betta, mine gets done 3 times a week.