Betta's caudal fin is half gone overnight!

[CPowers]

Literally overnight my betta's caudal fin is half gone. Attached is a picture from yesterday (4/16) and today (4/17). 

Here are the changes,.. fully cycled tank for the past 2 months, BUT I did an 80% water change to add a new substrate. The tank still has old filters, plants and decor. One detail is that the old water was dark (which I didn't like) from Almond Leaves. Temp is 78. 

 

Only tank mate is a nice little Rabbit Snail. 

 

Let me know what you think? API Water parameters are pH-6.6 AMM-0 NO2-0 NO3-0

 

Also, I think I may have hard water..which could be a reason his pectoral fins are crinckled. 

 

ANyways. If you can, I would love your thoughts.

Edited April 17 by CPowers

[AtomicSunfish]

Last time I saw a fish lose fins overnight was when my Oscar got a bacterial infection (columnaris). Might need antibiotics. Any trouble breathing? Is he resting on the bottom a lot? Or does he seem otherwise normal?

[CPowers]

@AtomicSunfish he seems fairly normal. I'll have to keep a close eye for changes. Did you have to also treat the tank as well? 

[Kurt Brutting]

I’ve heard some bettas eating their own fins. Have you seen any nibbling? 

[CPowers]

@Kurt Brutting a few months ago when I first got him I noticed his fins in his way when on his hammock and he made little nibbles, but nothing close to this amount and so dramatic. Wondering if he did basically eat his own fins should I treat the tank with anything to prevent infections. He still has like long thin string of fin left where it once was. 

[Kurt Brutting]

I would keep an eye on him and see if he is nibbling on himself. It just seems like a lot of fin went missing in one day. To provide enrichment you could put a mirror in front of him for 5mins to 10mins a day to get him to flare. That will exercise his fins. I’d hate to recommend Meds if that’s not the problem. Here is a really good video from Irene.  Keep me posted and good luck.
 

 

[CPowers]

@Kurt Brutting Thank you for the video rec. I actually just ordered those meds she recommended just incase it turns to an infection. I feel with 4 betta tanks, it's best to have it on hand anyways. 

[Kurt Brutting]

Good idea, I agree. If it gets worse you will be ready. Aquarium Co Op sells and makes the best product. 

[AtomicSunfish]

On 4/17/2024 at 6:16 PM, CPowers said:

@AtomicSunfish he seems fairly normal. I'll have to keep a close eye for changes. Did you have to also treat the tank as well? 

Yep, I treated the whole tank. Sounds like your guy may be nibbling on himself, though. Good advice above on providing stimulation and exercise. 👍