Why Are My Neon Tetras Dying? Help

  1. TagTeam

    TagTeam Valued Member Member

    20g tank, AquaClear 30 filter
    78 degrees F
    A-0, Ni-0, Na-0, pH-7.6 (just tested)

    As of 1:00 PM today I had:
    7 Neon Tetra
    2 Honey G
    1 Highfin Platy
    1 MM Platy

    8 hours later only 4 Tetras remain living.
    All the other fish seem fine.

    Anyone know what could be going wrong for the Tetras?
  2. KinsKicks

    KinsKicks Fishlore VIP Member


    Has the tank cycled? Unless you tested your water right after you did a larger water change (and your tap has no nitrates), you *shouldn't* have 0 across the board.

    And any external observations of the tetras before death?
  3. rohanr

    rohanr Valued Member Member

    Did they disappear or did you find the bodies? Any obvious marks on the fish or erratic behavior?

  4. OP

    TagTeam Valued Member Member

    2 disappeared.
    1 suddenly died right in front of me but then disappeared.
    I didn't notice any marks on him while he was dying.

    Yes, the tank has been cycled for about a week.
    I've had 0 across the board all week.
  5. rohanr

    rohanr Valued Member Member

    thats a lot of fish for only 1 week into the cycle! Did you use any booster bacteria?

    Neon tetras are also generally sensitive to water quality more than other fish. Them dying might be an indicator of a hidden substance on the water. The fish disappearing however, is probably the other fish eating them when they are dead.
  6. Starrone

    Starrone New Member Member

    Have you tested your water? Are they nippin each other. Any angel fish or larger tetras in with them. There could be so many reasons. For your sake I do hope you find the right answers. Best of luck?

    ;) I have to stay away from those lobstas. Now one’s on my hat!
  7. OP

    TagTeam Valued Member Member

    I used TSS and Prime
    I'm guessing I added too many fish too soon :-/
  8. rohanr

    rohanr Valued Member Member

    I think so, it’s fine, but for now all you can do is let it cycle out maybe killing some of your fish. Or you could return all of the fish, cycle it properly, then bring them back.

    Don’t worry about it, you should’ve seen the disaster of my first tank
  9. Taff

    Taff Valued Member Member

    Hi, keep doing plenty of water changes. Try 3 times 30% water changes starting today with an hour in-between.

    Then 50% each day, perhaps more if fish are showing signs of stress.

    Dilute down any harmful substances.

    Water changes are fish's best friend. Remember to use something to neutralise chlorine and chloramine.
  10. RonJ

    RonJ Well Known Member Member

    I think your test results are wrong. How are you testing? You won't have 0 across the board in a cycled tank. And definitely not in a tank that has been only running for a week.

    You should not be doing any water changes for 7 days minimum after adding TSS. If you have already done, you need to restart the process. I think your tank is still un-cycled and has high levels of ammonia and or nitrites. It's just that your current testing methodology is not detecting it correctly.
  11. Travis Bradbury

    Travis Bradbury Valued Member Member

    Neon tetras should be at a maximum temp of 75F.. just throwing that out there.. Not saying thats the reason their dying, but could factor in due to stress.. neons are extremely sensitive fish
  12. OP

    TagTeam Valued Member Member

    I’m using the API Master Test Kit
    I thought I was doing it right (I followed the directions very carefully each time)
  13. 86 ssinit

    86 ssinit Well Known Member Member

    Ok first off neons are known to die off when first bought. Neons are also not good as first fish because of the die off. Yes his reading could be right. My tanks are zeros across and my tap is also zeros across. Everybody’s water is different. So to the op this happens fish die. Now how are the other fish? You added tss so follow its instructions. Please don’t do those 30% water changes. Not knowing what your source water conditions are. How old is the tank?
  14. RonJ

    RonJ Well Known Member Member

    When nitrogen cycle is established the final stage is nitrites are converted to Nitrates. And those Nitrates don’t just evaporate. They need to be either taken out by the one who maintains the tank in the form of partial water changes or removed by other means. But 100% can not be removed by pwc of course. And if you are only doing a weekly water change just before the water change they will be usually in 20s or 30s or higher.

    Another way to remove Nitrates are through plants. Again not 100%. So any fully cycled plan oughta have at least 5PPM Nitrates. And a tank that only started Cycling 7days ago if shows 0Nitrate means the cycle has not even started fully and the last stage is not started yet (the stage where nitrites are converted to Nitrates). That also means you would have high ammonia or nitrites at that time. Hence the request to retest. Hope you understand now.
  15. OP

    TagTeam Valued Member Member

    The Honey Gs seem perfectly fine.
    The Highfin Platy seems ok.
    The MM Platy seems iffy.

    The tank is 2 1/2 weeks old

    That makes sense. I just tested again and got A-0, Ni-0, Na-0, pH 7.6
    Either I'm missing something on the instructions or ??
  16. Sacksteder kid

    Sacksteder kid Valued Member Member

    is this a new test kit or has it been sitting around awhile. I would definitely invest in a better testing system if you're still getting a row of 0's.
  17. OP

    TagTeam Valued Member Member

    It's a brand new API Freshwater Master Test Kit
  18. Sacksteder kid

    Sacksteder kid Valued Member Member

    Hmmph! well that sucks. Hopefully you're just reading the instructions wrong so you don't have to by a new test kit. If it's new enough you could try returning it.
  19. oOBlueOo

    oOBlueOo Well Known Member Member

    What was the ph of the store water for the neons? How new are they and how did you acclimated them to your water?
  20. Sel

    Sel Valued Member Member

    I'm 99% sure you would have an ammonia reading by now, especially with platys in your tank.