Strange Molly Behavior?

  1. Just A Fish Initiate Member

    Hi there. I own a 29 gallon tank that has six tetras, a lyretail dalmation molly, and her baby molly that is living in a smaller tank. As far as I can tell, the water levels are good.
    Recently, I have noticed my big molly acting strange. In the late afternoon, she will start to occasionally lean so far back that she is pointing straight up. She'll then vibrate rapidly before going back to normal. At times, a few tetras will even nip at her belly. Why might my molly be doing this and what can I do to help?
    On another note, would it be okay to add two more female mollies? In the past, big molly has been aggressive and caused the death of two other molly tank mates. I'm worried that she'll attack the newcomers or even vice versa, one or two of the newcomers will attack the others
    Please give advice. Thanks!
  2. el337 Fishlore Legend Member

    Can you provide your exact water parameters - pH, temp, ammonia, nitrite, nitrate? Do you happen to know your GH as well? The reason I'm asking is livebearers do better in hard water and from what you describe, it might be shimmies.

    I wouldn't add more mollies with her if she's been aggressive to others in the past.
  3. Aquaphobia Fishlore Legend Member

    Hi and welcome!

    Do you know what your water hardness is? Get the other parameters too!
  4. Adriifu Well Known Member Member

    My previous silver sailfin had a similar problem. He would swim in an upward manner. I did a lot of research on it and figured out that something was wrong with his swim bladder. I bathed him in epsom salt for fifteen minutes after quarantining him and he was better in a week. He never swam perfectly after this happened, but it was an improvement.

    I gave up on keeping mollies due to their aggression toward my other fish. If you've had the same experience, then I doubt it'd be smart to add more.
  5. Just A Fish Initiate Member

    GH is 0, KH is 40 mg/L, pH is 7.0, nitrite is at 0, and nitrate is at 30 mg/L
  6. Aquaphobia Fishlore Legend Member

    She could be suffering a neurological problem that livebearers can get if they're kept in water that's not hard enough. Especially with a GH of 0!
  7. Just A Fish Initiate Member

    My bad, both the GH and KH are between 40 and 60
  8. Just A Fish Initiate Member

    Apparently the readings were misread. The GH and KH are actually in between 40 and 60...
  9. el337 Fishlore Legend Member

    That’s still fairly low for GH which might be the reason for the behavior. I think you’d need at least 170. You also didn’t provide an ammonia reading?