**Important! Read this before posting if your fish are dying in your new tank**

[JustOneMore20]

You have a new tank and you’re fish are dying or acting funny. The main reason people have problems starting up a new tank is that they don’t know what cycling really is. Cycling is not just letting the filter run on the tank for a week without anything in it. Cycling is not putting the dechlorinator in the tank and running the filter or letting the tank sit with just water. You are NOT cycling the tank that way.

A cycle generally takes 4-6 weeks, but the time can vary from tank to tank. During this time, you are establishing colonies of good bacteria that will take care of ammonia in fish waste and decaying food and plants. The bacteria attach themselves to solid surfaces, including gravel/substrate, the glass, filter media, and decorations. There is very little bacteria in the water. The bacteria converts the ammonia into nitrite and then into nitrate, hence the name The Nitrogen Cycle. There are a few different types of bacteria that are established to do this job, but it’s not really important to remember them, just know what they are there for. The different bacteria appear at different times, which is why there is a pattern of ammonia rising and falling and then nitrites. Nitrates are not nearly as toxic in small amounts as ammonia and nitrite are and they are easily lowered by water changes, making the bacteria colony VITAL in a fish tank. Without the bacteria, ammonia rises, then nitrite and both are very toxic to your fish. As you can see, when starting a new tank, you have no bacteria colonies, so that is why fish die most of the time.

Now that you hopefully understand what is going on in your tank, you may be wondering what the best way to cycle a tank is. That really varies depending on what is available to you and what you are prepared to do.

Fishless Cycling
Fishless cycling is seen by many as the best way to cycle a tank. You can do this a couple different ways.
First, if you can find pure ammonia with no additives, scents, or colors you can use that. Add enough ammonia to the tank, to raise the level to about 3ppm. You really don’t need it too much higher than that. Add a little and test it. When it gets to 3ppm, leave it alone. Each day, add the same amount of ammonia that you did the first day. After a few days to a week, start checking for nitrites. You’ll see a rise and fall of ammonia, then a rise and fall of nitrites, and then finally nitrates. After awhile, you may not need to add ammonia daily, but you still need to add it every other day or so to keep the bacteria fed. Once your nitrates are over 1ppm, keep adding the ammonia every other day or so until you are ready to buy some fish….then do a water change (around 40-50% would be good) and add your fish (after acclimating).

Another method of fishless cycling is using a c0cktail shrimp from the grocery store/market. I suggest putting the shrimp in a pantyhose/knee high/stocking so that it doesn’t make a mess in the tank. It may smell, but at least you are sparing your future fish from the toxic ammonia and nitrite. With this method, there is no daily dosing. You will still need to check the ammonia for the first few days to week and then start checking nitrites for a few weeks and later check nitrates. You will see the same rise and fall of ammonia and nitrites, as with any cycle, until they reach 0 and you have some nitrates.

Cycling with Fish
If you choose to cycle with fish, or you already have your fish and you cannot get rid of them or trade them in, here is some information to make it go as smooth as possible. First, make sure the fish you have are considered “hardy”. This means that they are not as sensitive as other fish and are able to handle a cycle better. This doesn’t make it right to expose them to ammonia and nitrite, but they have a better chance of surviving if they are hardy. If you have fish/inverts that are more sensitive than others (Corydoras, loaches, shrimp, Discus…..etc.) you should try your hardest to find a pet/fish store that will take them for some credit or find a friend that has a cycled tank (0 ammonia or nitrite, more than 1ppm nitrates consistently). They will likely not survive the cycle, so you should not keep them in the tank. Next, find out how many watts your light fixture is. Why do you need a light fixture, you may be wondering? Live plants are great to add during a cycle because they also take in ammonia. Fast growing stem plants are the best to use, but you need to have adequate lighting. Plants like Anacharis, Hornwort, and Wisteria will grow in very little light and are fast growers. I suggest getting a lot of these plants to add to the tank during cycling with fish to help with the ammonia levels. Be prepared to do a lot of water changes during this time and test your tank daily for ammonia and then nitrites. When you have more than about 0.25 to 0.5ppm of either, do a small water change with dechlorinated tap water.

Silent Cycle
If you start out with a planted tank, you can do something called a silent cycle. This involves planting the tank initially with a lot of fast growing plants and adding fish slowly. I would have atleast a moderately planted tank for this, so you’ll have enough plant mass to take care of the ammonia. Add in about 3 fish per week, monitoring for ammonia and nitrites and doing water changes as needed. You may not see any ammonia or nitrites and this is good. Eventually you’ll see nitrates and you’ll know you’re cycled. This is usually pretty fast, compared to traditionally cycling.


If you read this article and you are still wondering why you are losing fish, check your water parameters. I suggest getting a liquid test kit like the Aquarium Pharmaceuticals kit. It is a great investment that will last you a long time. Liquid test kits are more accurate than strips and actually give you a number for the parameters instead of a “dangerous” or “safe” zone that you have no idea what they consider to be in that zone. I do not recommend using these types of strips. Once you have tested your water, if you have ANY ammonia or nitrites, that is likely the cause of your fish problems, unless you see signs of disease. Do a water change and keep testing the ammonia/nitrites a few hours after the water change and then daily afterwards.

If you still need help and your question isn’t answered in this article, then you should post a thread for help. ***Make sure you test your water parameters before hand and post them, as well as you tank size, fish, how long your tank has been setup, and any other information that you think might be useful (how long you’ve had the fish in question).*** If you have a disease issue, please put that thread in the appropriate forum.


Reference: http://www.cichlidforum.com/articles/cycling.php

*If you have anything to add or change, please respond to this thread. Otherwise, please read it and ask any questions about your tank or cycling in a new thread.