We got 2 'female' betta fish for our tank over 6 months ago.

Until a few weeks later their fins grew bigger and they are both males.

I thought we were lucky and they seemed to get on ok.

Until the yesterday we came home to find one still just about alive and the other fine. He is being very aggressive now as the other is vulnerable.

I don't really know what to do..I'm going to try and go back to the fish shop tomorrow and see if they could help.

Until then I have put one in the net in the water still with water flow will this be ok?

I don't want to see the other one get eaten help!

  • 4
    Separate tanks.
    – keshlam
    Jul 29, 2015 at 21:41
  • 1
    Gotta agree with @keshlam here. Male beta fish are solitary animals and will fight (generally to the death) if in a tank together. Your only real long term option is to get a separate tank. Jul 29, 2015 at 22:45
  • 3
    They are called Siamese fighting fish for a reason
    – Keltari
    Sep 25, 2015 at 6:40
  • separate tanks or bring one back to the store
    – Manuki
    Mar 7, 2019 at 20:57

3 Answers 3


Only female beta fish can be housed together (relatively) peacefully. As soon as male fish come into their juvenile stage they will fight, and usually to the death. This is one of the reasons why they are sold in urine-sample sized cups in mass at pet stores (though it is not recommended for long-term).

Please see the other comments to your question, they are correct in saying that you should put them in separate tanks.


I'm also a Betta owner and I breed fish. One day, my female attacked my male. What I did was removed him from the tank and put him in a separate tank. In my opinion you should do whatever it takes to keep him safe.


If your tank is large enough (10 gallons or more) you could use a divider to split the tank in half. If you go this route you'll want to make sure the divider is opaque too, or put lots of plants/décor by it, so that they don't generally see each other. You'll probably also have to have a filter going on each side of the divider - each rated for tanks half the size of your whole tank (since bettas aren't terribly strong swimmers, they can quickly become exhausted if the water is too turbulent).

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