Cycling new tank

  1. mocker Initiate Member

    I'm cycling new tank (my first one) using raw fish.

    Several week passed and I'm getting nitrites and nitrates readings now.

    As far as I understand, I should remove raw fish now and change water (25%)?

    How long should I wait before adding live fish (after I remove the raw fish)?
     
  2. Wendy Lubianetsky Well Known Member Member

    I would take the fish out do a 25% water change and keep cycling until ALL the nitrites are gone. Not until then can you put fish into the tank.
     

  3. toosie Well Known Member Member

    Welcome to FishLore!! :sign0016:

    Actually you should leave the raw fish in until you no longer detect nitrites and only have a level of nitrates. When that happens, do a large enough water change to bring the nitrates down to 20ppm or lower and then you can add live fish.

    The reason you leave the raw fish in is to continue feeding the bacteria that converts ammonia to nitrites. If you remove it prematurely, you could end up with an ammonia spike when you add live fish because the BB that is responsible for converting the ammonia to nitrites will have deminished and will no longer be strong enough to handle the fish waste load.
     

  4. catsma_97504 Fishlore Legend Member

    Welcome to Fishlore.

    I agree with toosie as you need a constant ammonia source to not loose the bacteria that can process ammonia. A tank isn't fully cycled until there is no measurable ammonia or nitrite.

    Once this occurs, you can do a very large water change and then only add a fish or two to avoid overloading the new cycle.

    If you wouldn't mind, please provide complete Aquarium Profile Information. This information will help the members to gain an understanding of your tank. Just click the My Settings button at the top of this page, and select Edit Aquarium Info. Complete the information on your aquarium, including tank size, filtration, stocking, lighting, water parameters, etc. And save your changes. Then you won't be inundated with answering questions about your tank.

    Congratulations on the fishless cycle.
     

  5. Wendy Lubianetsky Well Known Member Member

    :eek: Once again what I did was wrong..... thank you for correcting me. It did work for me however. I used that method on my sixth tank and it seemed to be okay, I guess I was lucky. ???
     
  6. toosie Well Known Member Member

    If it doesn't take too long to get through the nitrite portion of the cycle, the bacteria for the ammonia portion, or at least maybe enough of this bacteria may still be active enough to take care of the amount of ammonia created by the amount of fish that are introduced. The bacteria doesn't die off or go into a dormant state right away, but it is impossible to predict how long they will remain active enough to continue to be able to take care of the ammonia from live fish if they aren't continuously fed.

    The nitrogen cycle is a hard one to predict at the best of times and every tank is different as well as how heavy a tank is initially stocked with what type of fish can play a large part in how much bacteria needs to be available. So... I wouldn't say you were only lucky but you weren't unlucky either. :D You are learning a lot Wendy and you are doing a good job with your tanks.