View Full Version : Cycling with Fish

Lady Hobbs
01-21-2009, 07:21 PM
Cyling with Fish

Once you start to cycle (all methods) do no cleaning of the filter media or the gravel. You are growing bacteria in those areas and that bacteria is what cycles your tank. This can not be stressed enough. Also, not use ammonia removers or pH adjusters or other chemicals except your water conditioner that removes chlorine and chloramines. You may use a bacteria booster if you wish to help the fish tolerate toxic water a little better but keep in mind these booster do NOT cycle the tank for you. They do not take the place of the water changes you still will need to do.

Do not try to cycle a tank with any bottom feeders or sensitive fish.

The purpose of cycling a fish tank is the production of "good" bacteria that eats the ammonia and nitrites that kill the fish. Ammonia eating bacteria is called Nitrosomona and the bacteria that eats the nitrites are Nitrobacter. They grow in your filter media. Having these bacteria's are what is known as a cycled tank. These bacteria's grow faster in warmer temperatures with lots of oxygen so turn your heater up to 82 and add an air stone or bubbler.

Unless you have well water, you must always use a de-chlorinator. Some even use water conditioners with well water as it removes the heavy metals that may be present. The chlorine in your water supply will kill bacteria immediately. Many water municipals also use chloramines as a means of sterilization so get a product that removes chlorine and chloramines. Most de-chlorinators do both but read the label. Some “age” their water to remove chlorine. However, storing water does not remove chloramines.

Fish produce ammonia from their gills, from rotting food in the tank and from their waste. Ammonia continues to build up until the water becomes toxic and kills them.
If you cycle with fish, it must be with extreme caution, daily testing of the water and doing many water changes to make sure the ammonia never climbs over .25-.50 maximum. (Some fish can not ttolerate even this level.) This is why test kits are vital so you know what the toxic level is in your tank. Bacteria does NOT grow in the water so do as many water changes as necessary.

After you have a low ammonia level for a time, you will began to see nitrites register on your tester and the ammonia will began to go down. Nitrites are also toxic and water changes and testing must continue.

As you reach a cycle....0 ammonia and 0 nitrites.... you can again add a few more fish and once again cycle with the new additions. This must continue on after each addition of new fish until you have your tank stocked as you wish. You only grow enough bacteria in your filter media to support what you have in the tank.

If you began with too many fish at once, you will have very high levels of ammonia’s and they will likely all die so this stocking must be done carefully.

Never plan on a fast cycle when cycling with fish. It can take a couple months compared to a couple weeks fish-less cycling. Smaller tanks get more toxic than larger tanks due to the water concentration so be very careful in how much you stock when starting out.

The better filtration you have, the more space you have for "good" bacteria to grow. Feed the fish sparingly. Rotting food in the gravel only adds more ammonia to the tank and fish eat far less than you think.

01-04-2015, 07:53 PM
I thought I would add a little extra explanation of the above instructions

When it comes to completing waterchanges, you should complete one whenever your ammonia and/or nitrites get above 0.25ppm to 0.5ppm.

When completing a waterchange, you should base the amount of the waterchange on your test results changing enough water to bring the levels back down to 0.25ppm or less. For example, if your ammonia or nitrite is at 0.5ppm, you will need to complete a 50% water change to lower the levels back down to 0.25ppm. If the ammonia or nitrite was at 1ppm, then you will need to complete a 75% water change to lower it back down to 0.25ppm.

In extreme situations, more than one waterchanged could be needed. If the ammonia and/or nitrite levels were to reach 2ppm, then two 75% water changes completed within about 20 minutes of each other would be required. However, if you are checking your ammonia and nitrite levels daily and staying on top of any required waterchanges, you should not find yourself in this situation.