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Fish Keeping for the Complete Beginner :)

So, you bought a 10 gallon starter kit, got some (probably bad) advice from the people at the pet store, threw in some fish, and got ready to enjoy your aquarium...only to find out that it’s a lot more complicated than you thought! This is not the best way to set up a new tank, but it is what 95% of us have done. If you feel lost or totally confused, this blog is for you! By the end you should have a basic understanding of the nitrogen cycle, and know what to do to keep your fish alive until you get through it!

*The Nitrogen Cycle*

Just like us, fish produce waste when they breathe and when they excrete. This is usually in the form of ammonia. Excess food and rotting plant matter can also produce ammonia. We use ammonia in cleaners because it is toxic. Too much ammonia will kill your fish. Thankfully, some bacteria will eat ammonia!

This is the first step in your cycle. Once ammonia is present in your tank, either from fish waste or some other source, bacteria will begin to grow that eats the ammonia. This bacteria produces nitrites as waste. Unfortunately, nitrites are also toxic. Thankfully, a different kind of bacteria will eat nitrites!

This is step two of your cycle! Once, your ammonia eating bacteria is established, nitrites will show up in your tank, and bacteria will start growing to eat nitrites! This nitrite-eating bacteria produces nitrates as waste. Thankfully, nitrates are less toxic than ammonia or nitrites, and a third kind of bacteria will grow that eats *some* of the nitrates.

Once this process is complete, so long as you keep up with routine maintenance, your tank is good to go!

*Monitoring the Nitrogen Cycle*

So how will you know when all this happens? The *best* way is to purchase an API Master Kit (freshwater). This will let you test your water for ammonia, nitrites, and nitrates. You should probably also by some Prime water conditioner (by Seachem) to help you through the cycle.

When you are testing your water, you should see your ammonia start to rise. As your bacteria grows, ammonia will go up, then down to zero. Then you will see nitrites. Then nitrites will go up, and then down to zero. Then nitrates will go up. At this point, if you have 0 ammonia, 0 nitrites, and you do a water change to get your nitrates under 40, your tank is cycled and you are ready to go!

*Keeping Your Fish Alive During the Cycle*

As previously mentioned, ammonia and nitrite are how do you keep your fish alive through this process? WATER CHANGES!

There are two schools of thought on this process. One is that you should do a 25 percent partial water change whenever your ammonia or nitrites reaches .50 parts per million (ppm).

The other is that you should use a water conditioner that detoxifies ammonia and nitrites (such as Prime), and do a water change whenever your ammonia or nitrites reaches 1.0 ppm.

I think, in terms of completing your cycle, that it is better to go the 2nd route. This way your bacteria can grow faster, and as long as you are diligent about monitoring your water and adding Prime (it will detoxify ammonia/nitrites for approximately a day and half), it is better to wait and do water changes less frequently.


It seems like a lot of work, but don’t be intimidated! The reality of the situation is that you will probably do a couple of small water changes per week for a few weeks. After that, you can do a 25 percent water change once per week and (assuming you haven’t over-stocked your tank), it should (pretty much) be smoothe sailing from there!

Good luck and hope that helps!


So... what do you think? Please leave me a comment or give me a


  • kthorkel: Very well written and easy to understand.
  • johnarthur: Well done!
  • Paul888: Good work there mate!
  • jephil0: I was going to call it "for Dummies..." But I figured there was a trademark issue there!
  • daniolover: thank you! it makes complete sense now! that was me , loads of fish, small tank, argh!!! these poor fish. ive lost 2 guppies so far :-( i understand why now and am on the case. thank you so much.
  • daniolover: i have started up a fishless cycle in a new tank , as well as my fish tank i am already cycling, so i can see how it is meant to be :-)
  • Ashley: Hi Jonathon! I have a very large spike in Nitrites in my 20 gallon Guppy tank.. I read your post.. So as far as the second conclusion, do a water change when nitrites get back down to 1ppm or up to 1 ppm?? I have been reading about this alot and am determined to make my fish safer! I have never had this problem last out of my control..
  • Karl m: WIsh i had seen that when i was starting out its a really good read and is definitely going to help a lot of ppl. Good job
  • jephil0: Do the water change when your nitrites get UP to 1.0. So if they are higher than that now, you need to do some water changes to get them down. After that, you can temporarily use Prime to detoxify the nitrite.
  • ashley m: Thanks for the rapid reply! Nitrites wont budge! Been doing water changes daily.added established gravel and plastic plants....any other suggestions? I also have a prego ready to burst! She had 2 fry so far but holding in the rest i think because the water conditions..any other suggestions to bring down the nitrites?? My guppy seem okay so far...its a 20 gallon all guppy..lighted aerated filterated..1 live plant.. my amonia/0. Nitrites /5+ nitrates /0 ph 7/.4 tank already did cycle weeks ago.. i have a 150.2 55s.a 5gal hospital with new. fish in at moment..also guppies.any other suggestions??
  • Justin: This whole site has been a lifesaver! I remember (my parents) having an aquarium as a kid and it’s been years since I’ve had contact with one much less the responsibility of one. My daughter won a gold fish @ her fall festival. First I just bought a starter 1 gallon bowl... That was cool. Then I thought "Ya know, I should get an aquarium and some other fish. I remember loving it as a kid" ... So I did what Jonathan described buying a 10 gallon LED aquarium.
    I had NO idea about the nitrogen cycle, and read some other posts on here over the past week before I got to this one. I went to the pet store yesterday and bought the API kit, Prime and Stability.
    The Ammonia levels were close to 8 ppm the PH is at 7.6
    Nitrites 0
    Nitrates looked to be at around 2.5 ppm (that one was a bit hard to read.) [this is after a 25% water change treated with prime, stability, and Aquasafe before I read this]
    I dosed the tank with prime yesterday, and again today.
    I’ll be monitoring daily, but before I got to the pet store I lost 1 of the 2 Mollies I had. I have 5 Zebra Danios, 2 striped tetras, a Neon tetra, and a plecostomus. And Nemo the goldfish (my 7 year old daughter named it).
    I’m trying not to over do it with the treatments, but stay diligent at the same time. Any advice is welcome. I’ve skimmed a lot of posts here already. Thanks!
  • jephil0: You will get better responses posting on the forum. :) That said, in brief, goldfish are really messy fish. You could keep a baby goldfish in a 10 gallon tank for a short time, but they get big, you will likely quickly want a bigger one.
    Your 10 gallon is too small for that many fish. If you want to keep the goldfish, your best bet is to get a bigger tank and put him in it by himself. Your plecostomus will be a problem too, as they can get two feet in size.
    Normally, I would say don’t change more than 25 percent of the water at a time. However, if your ammonia is at 8 ppm, you are in an emergency situation! I would change 50 percent of the water immediately. Make sure to use a water conditioner and temperature match the water (stick your finger in it to get the temperatures basically the same). That will bring you down to 4 ppm. You will need to do the same thing every day until you are under 1 ppm, at which point the Prime will be better able to help while your tank cycles. That said, with all those fish, I don’t know if it CAN cycle... They will be producing a LOT of ammonia for a relatively small tank.
    Sorry! Wish I had better news! Good luck!
  • Cheryl: A friend gave me a 10g tank The lfs told me to use nutria fin wait a week and I’m good to add fish. So I bought 4 small fancy goldfish, you can guess what happened after that, everything spiked. I knew they needed a bigger tank . I bought a 45 bow had to get fish out of the small tank so I put them in the larger tank. So now I know how to cycle and do water changes( I learned along the way thanks to sites like this one ) My question is when I’m doing my many water changes do I vacuum the gravel? I have been, maybe that’s why my nitrites are staying so high? My fish are still looking pretty happy so far. Thanks for your time.
  • Vale: This is a brief note to anyone asking a question here: Copy and paste your question into the green "Ask a Question" box in the top right corner of the page and click the yellow "Submit" button. This will open a new question in the forum - you’ll get a lot more replies in the forum than as a comment on a blog! Good luck!
  • jephil0: Convential wisdom is that you vacuum no more than 1/2 the gravel at a time. I would do 1/3 and see how that works out for you.
    Also, as Vale said, you will get more and better responses by posting your questions on the message boards instead of here, because here, your answer is from just me, where as the boards have TONS of people who can help with all kinds of problems. :)
    Hope that helps and good luck!
  • lea: this is GREAT - thanks for posting :)
  • DoctorJ: Way to go!
    Where are the other parts? :)
  • Fishfur: Unless tanks have a working deep sand bed with an established anaerobic layer, there are only two kinds of bacteria working in fresh water tanks. There ARE bacteria that eat nitrate. But they only survive where there is no oxygen. Fresh water filters and the gravel have plenty of oxygen, so the only bacteria working in most freshwater tanks are the ones that eat ammonia and nitrite.
    Nitrate is controlled by water changes or plants using it up, or by special filter media you can use, which will absorb nitrate along with other toxins. Seachem’s Purigen does this. Not cheap, but it does work. Or you can buy a special denitrifying filter that does have anaerobic bacteria in it, and does digest the nitrate.
  • Heatherglo: Great blog,
    Fishfur great addition :) always love what you bring to the table
  • Fishfur: I only recently became aware of another Seachem product, Matrix. This is said to have such deep recesses and holes in it that anaerobic bacteria can become established in it, in a regular FW filter system. The anaerobes are protected from oxygen by the complexity and depth of the pores in Matrix, and once they become established, Matrix is said to remove nitrate too, thereby acting as true denitrifyer.
    I have not yet tried Matrix, and do not know if it works as advertised. But I have always been pleased with most Seachem products I’ve tried, so I am thinking I may give it a try.
    It would be nice not to have to be as concerned with nitrates, though it would be no excuse to skip water changes. It may be useful for tanks where the keeper is struggling to control nitrates for some reason.
  • Chris: Great information thank you!!
  • Heatherglo: Ty fishfur keep us posted ;)
  • Goldfish Luver: Thanks for the awesome idea

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