Sarge1: Crowntail Betta, Originally uploaded by Aimzee.
Healthy crowntail male Betta splendens.

Q: N wrote,

I think I have a tail biter. His caudal fin is shredded and there is nothing in the tank that could be doing it to him. No sharp plants or other fish. I have dealt with fin rot before with another betta and it doesn’t appear to be that either. Ammonia is 0, nitrite is 0 and nitrate is 12 ppm.

A: Well, it’s not totally unheard of for Bettas to bite their own tails. I personally haven’t dealt with it but I hear about it from others. I suspect that in most cases the ragged fins are a result of poor water quality or injury from tank decor or other fish. Too often people believe their betta is biting his own fins when the problem is environmental but in your case, I think you might be right. Based on the water parameters you provided, your tank is fully cycled and in good shape, at least as far as ammonia, nitrite and nitrate are concerned. If there are no sharp rocks, plastic plants or heavy filter suction to catch his fins then it’s possible he is doing it to himself. I recommend observing him closely to see if you can catch him in the act.

The reason Betta’s bite their own fins is unknown. Some say it’s stress, others say boredom and still others think it could be hunger, pent up aggression or even hereditary. The truth is, we just don’t know. There are a few things you can do to help him along. First, continue to keep your water very clean to avoid infection. Some Betta keepers have successfully broken the habit by changing the aquarium decor around or by adding more silk or live plants. Adjusting the light levels may be useful too reduce reflections which may fuel your Bettas aggression. If your aquarium is large enough, you may find adding a few peaceful community fish will keep your Betta occupied.

In addition to clean water, you can also add Pimafix or half strength Melafix to the tank to help regenerate fin growth. If your betta reacts to the medication negatively, discontinue use.

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Reader Interactions


  1. Anonymous says:

    I have personally had a few tail biters. Drives me nuts.
    One…did it after having it for a couple of years. He just decided one day it would be a good idea.
    He never stopped, unless there wasn’t enough to bite off anymore. Then he would let it grow a little, just so he could bite it off again.
    Another male did it out of frustration. I moved his favorite “flare” buddy and started chewing himself up. Put his “buddy’s” tank back next to him and he quit chewing himself up.
    Another male (recently) decided it would be a great idea to bite his tail while waiting to be fed. Dork.
    I now feed him first,and have the bloodworms all ready to be dropped in his tank before I even walk into the room.
    Most of the ones that quit have had their tails grow back, except the one that never quit.

  2. Christie says:

    Wow, it sounds like your bettas have been a total handful. Well, I guess if they didn’t challenge us, we wouldn’t be as crazy about them. 😀

  3. Anonymous says:

    I just watched a betta biting off his own tail so it definitely happens. The guy was well fed so not from hunger and he could not see other bettas. He could have been board or thought his tail was another betta or who knows what.

  4. zoey says:

    One of my gold fish bit my betta fins of what can i do? I already put him [Weedy] in a septet tank what can i do more?

    • Christie F. says:

      Separating the fish right away was a very smart idea. Betta fins will heal but you’ll have to watch for infection. Increase your water changes and remove any decaying debris from the water each day (like uneaten food, fish poo or dead plant matter). You may also want to consider using an antiseptic like API brand BettaFix which works well to speed up the healing of open wounds and torn fins. It is very inexpensive and can be found at almost any fish store (depending on what country you are in.) You may want to keep your betta in his own tank from now on. Bettas and goldfish aren’t really compatible. We have an article about it if you’d like to know more. ARTICLE: Housing Bettas with Goldfish Good luck, I hope he gets better soon.

  5. Jaime says:

    My betta just began biting his tail. Ive had him for a little over 2 months, hes a double tail half moon. I had him in a 6.6 gallon tank and he began resting on his filter intake. This started shredding the finnage…I moved him to a 3 gal with a baffled filter, it didnt help, he still managed to find the filter intake…one day I came in and his enture dorsal fin was gone, sucked in by the filter and ripped off, he kept hiding under the plants and was acting completely off. I moved him to a 1.5 gallon bowl for treatment, did 10 days AQ salt and IAL leaves. His dorsal fin began to heal really nicely, but now hes begun tail biting! I think it has a lot to do with the small space :-/ …Ive been reading that small spaces often help with tail biters, but perhaps he actually needs a larger space? Do you think this could be true? I bought a 10 gal yesterday and plan to set it up for him this week with live plants. Any thoughts on this? Water perams are fine in the hospital tank and he is heated 🙂

  6. amanda says:

    I once read that some bettas bite their tails because a long tail slows them down when they’re swimming. My betta also bites. I’ve watched him before swimming in circles, nipping at his tail. As long as the tank is clean, and the the tail isn’t getting infected or fin rot from the behavior, I don’t think its too much to worry about. It is a bit sad that I won’t have a betta with a beautifully grown out tail and fins, but he’s healthy and still fun to watch when I should be doing homework, like right now.

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