I just got a Betta fish a week ago, and it looks like it has fin rot--the fins are ragged looking and getting worse, but

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Customer: I just got a Betta fish a week ago, and it looks like it has fin rot--the fins are ragged looking and getting worse, but they aren't dark at the ends, so I'm wondering if it could be that the fish is biting it's own fins. If that's the case, what can I do about it?
JA: I'll do all I can to help. Does the betta fish do this all the time or only sometimes?
Customer: I haven't actually seen him biting at his fins.
JA: Have you tried anything so far that helps the betta fish with this behavior?
Customer: No, I don't know what to try.
JA: And what's the betta fish's name and age?
Customer: His name is ***** ***** he's 2.5-3 months old.
JA: Is there anything else the Vet should know about Jerry?
Customer: He's my first Betta, so I don't know if this is normal, but he has seemed a little frantic, swimming back and forth along the front of the tank, especially when people are nearby.
Answered by Anna in 12 mins 2 years ago
30+ years of experience

17,040 satisfied customers

Specialities include: Dog Veterinary, Cat Veterinary, Bird Veterinary, Reptile Veterinary, Exotic Animal Veterinary

Hello and welcome. My name is ***** ***** I’m a biologist with over 40 years of experience keeping fish. I’m sorry to hear about this problem. Fin rot is much more likely than him biting his own fins. Can you send me a picture of him? You can upload a photo by clicking on the paper clip icon in the toolbar at the top of the space where you type. Instructions should pop up. Thank you.

Customer attachment 5/8/2020 7:06:09 PM

Thank you. I’ll take a look and be right back.

He finally stayed still for a second and I got this better shot of his fins:

It would be very difficult for him to reach some of those fins to bite them, especially the one on his back. I also see a few white edges, which is another fin rot symptom. Even if something else happened to his fins, once they are injured, fin rot is likely to develop. I would treat for fin rot. It has become extremely common in bettas. Once it develops, it can become chronic and require treatment over and over.

You can try treating with something mild to begin with, such as Bettafix. If that doesn’t help, you’ll need to go to a stronger medication, such as Kanaplex. Here is an online source if you end up needing it:


Just got your new photo. Be right back.

That looks like fin rot to me.Fins don’t always turn black until it is very advanced. Because it can be so hard to treat, and you just got the fish, you may be able to return him. However, if you’re already attached, you’ll probably prefer to treat him. If you have more questions, just let me know. I’m glad to help.

We got aquarium salt, since that was what most websites recommended for treating fin rot. But you recommend Bettafix instead?

Aquarium salt seldom works by itself. I would use it and Bettafix. They are safe to use together.

Great! We also read we should use a smaller (2 gal or less) hospital tank to treat him. (He's currently alone in a 5 gal tank.) And I've read we should change the water 100% every day for a week if we're using aquarium salt. Is that what you'd recommend?

Since he’s alone, there’s no need to move him to a hospital tank. There are two reasons we use such a tank.One is not to subject other fish in a tank to medication they don’t need. The other is to cut down on in the cost of medication.

There is no need to change the water when using aquarium salt. Just don’t add more salt. Put it in just once. Then follow the instructions for the Bettafix regarding water changes.

That is so helpful! Thank you!!

You’re welcome. If you want to read the Bettafix instructions, here they are:


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