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jake_planted
Beginners & cycling (freshwater)jake_planted

20 gallon community tank, how long should I wait before adding fish?

Setting up my first real freshwater tank, 20 gallon long. I have the filter running, heater, and I added some gravel and a few fake plants for now. I might try real plants later. I keep reading different things about cycling. Some people say wait a month, some say you can add fish sooner if you use bacteria starter. I picked up API Master Test Kit yesterday but I have not tested yet. Goal is a small community tank. Maybe tetras, a cory or two, nothing crazy. I do not want to rush it and kill fish on week one. For anyone who did a 20g community recently, how long did you wait and what did you test for before adding anything? Also is it worth using bottled bacteria or is that hit or miss? Thanks in advance.
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Replies(8)

  • morgan_tanks
    Replymorgan_tanks
    I would wait until you see ammonia go up and then back down, and nitrite do the same, before you add fish. On my last 20g that took about 3 weeks without fish in the tank. Could be faster or slower for you. Test every few days and write it down. Ammonia, nitrite, nitrate. When ammonia and nitrite read 0 with some nitrate showing, you are usually good to start slow. Bottled bacteria helped me once and did nothing another time. I still use it sometimes but I do not rely on it. The test kit matters more.
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  • chris_aqua22
    Replychris_aqua22
    Second what morgan said. If you can, fishless cycle with a small daily dose of ammonia or use fish food and let it break down. Way easier than losing fish while the tank catches up. Do not add a whole school at once even after the cycle. Start with a small group, wait a week, watch your tests again. A 20 long is easy to overstock. Also run the heater and filter for at least 24 to 48 hours before you trust any reading. Tap water temp swings can throw you off at first.
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  • sammy_fins
    Replysammy_fins
    i made the mistake of adding fish too fast on my first community tank. lost a few tetras and felt terrible. now i wait for 0 ammonia and 0 nitrite even if the bottle says you can add fish in 24 hours. for a 20g i would do like 6 tetras max to start, then corys later. corys are messy for their size so dont go crazy. platties are hardy too if you want something a little bigger. good call getting the test kit early. that saved me on my 29g.
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  • l_rivera
    Replyl_rivera
    We have a 20 gallon in the living room and I made the kids wait almost four weeks before anything went in. I explained it like letting the filter grow good bacteria first. They were impatient but it was worth it. Very little drama since then. For kid friendly options we liked platties and a small group of neon tetras. One albino cory. We feed lightly and change water every week or two. If you stay with fake plants for now that is fine. Real plants can help once you are stable but they are a whole other learning curve.
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  • jake_planted
    Replyjake_planted
    This is really helpful, thank you. I am going to test tonight after work and start logging it. I will probably fishless cycle and hold off on buying fish until ammonia and nitrite stay at zero. I was eyeing like 10 tetras and 3 corys at once so glad I asked. I will start smaller. Might post my test results in a few days if I am not sure I am reading the colors right.
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  • morgan_tanks
    Replymorgan_tanks
    Sounds like a good plan. Snap a photo of the test vials in daylight if you are unsure, easier for people to chime in. Also pick one food and stick with it for a while. Flakes vs pellets is not a huge deal but switching a lot can make a new tank look worse than it is.
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  • chris_aqua22
    Replychris_aqua22
    If you go tetras get a school of one type first. mixing neons and black neons and stuff on day one in a new tank is a lot. one species, small group, then expand. you got this. boring first month usually means a healthy tank later.
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  • sammy_fins
    Replysammy_fins
    yeah boring is good lol. good luck jake, update when you get your first 0/0 reading
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