# Recommendation for adding a big fish load?



## solarz (Aug 31, 2010)

I have a 20gal planted tank with a 3 guppies and some shrimps right now. I'm thinking of adding 9 cardinal tetras in the future. I don't want the tank to undergo another cycle after I add the cardinals, so I'm looking for any advice on how I can prepare my tank to receive a big fish load?

I would prefer to be able to add all the fish at once, as I am hoping to take advantage of special prices.


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## gucci17 (Oct 11, 2007)

How long has your tank been running?

9 cardinal tetras are a very low bioload, especially in a 20gal. You will be ok as long as your tank is fully cycled and mature.


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## solarz (Aug 31, 2010)

gucci17 said:


> How long has your tank been running?
> 
> 9 cardinal tetras are a very low bioload, especially in a 20gal. You will be ok as long as your tank is fully cycled and mature.


My tank has been running for about a month. I am still getting small amounts of nitrite. I am willing to wait, but I'm worried that my tank will reach an equilibrium for my current bioload (only 3 guppies and some shrimps), and will undergo a new cycle when I practically triple the bioload.


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## gucci17 (Oct 11, 2007)

If you don't want to invest in a test kit, I would just wait a little longer if there's no rush. TBH, 9 cardinals will add very little to your bioload.

What type of filtration are you running?


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## solarz (Aug 31, 2010)

Where did I say that I don't have a test kit? I'm using a HOB filter. And like I said, what I'm worried about is the tank will only develop enough biofilter to handle my current load, and that suddenly tripling the load would cause the tank to go into a cycle again. Waiting longer won't change anything.


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## gucci17 (Oct 11, 2007)

Sorry, I didn't mean say you didn't have one. Came out the wrong way, I apologize. Since you do have a test kit, what are you current parameters? 

What HOB filter is it? Brand/Model?

If your tank is stable and fully cycled, I would go ahead with adding in the cardinals. I'm assuming you are aware that cardinals/neons are very sensitive and need to be acclimated slowly when introduced to a new tank with different parameters. I've had groups where I bought locally from another member with no casualties whereas, I have imported and left with a few out of 100. 

As for your comment about waiting longer won't change anything. I beg to differ. It's somewhat true what you're saying about filters being able to handle their 'current' bioload. But in my experience, I have had no problem adding fish into a well established tank and filters. Just make sure your filters have the capacity to handle a higher bioload. Or, seed another filter and have it ready.


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## pat3612 (Jan 29, 2008)

I have always found that tetras like a well established tank too I would wait at least another month to . I have never added them in anything less then a 6 month old tank though. Also you should get those nitrites down to 0


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## solarz (Aug 31, 2010)

So you guys think that if my tank is cycled, my planned addition of 9 cardinals shouldn't be a problem?


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## solarz (Aug 31, 2010)

Good news, last night my nitrite went down to 0, and I also have 0 ammonia. How long should I wait for now before adding more fish?


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## waj8 (Jun 30, 2010)

Fully cycled just means that the nitrifying bacteria have reached a big enough population to deal with your Nitrite and Ammonia load. If you add more fish then the colony has to get bigger to acommodate the extra Ammonia and Nitrite that will be produced. So, a tank is not either cycled or not cycled. It's a process that is on-going.

Probably, there will be no problem adding the extra fish as long as you have a filter that has enough bio media capacity but you will have to stay on top of the testing and be prepared if something shows up. Personally, I would just wait. Cardinals are not very good fish for cycling.


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## solarz (Aug 31, 2010)

waj8 said:


> Fully cycled just means that the nitrifying bacteria have reached a big enough population to deal with your Nitrite and Ammonia load. If you add more fish then the colony has to get bigger to acommodate the extra Ammonia and Nitrite that will be produced. So, a tank is not either cycled or not cycled. It's a process that is on-going.
> 
> Probably, there will be no problem adding the extra fish as long as you have a filter that has enough bio media capacity but you will have to stay on top of the testing and be prepared if something shows up. Personally, I would just wait. Cardinals are not very good fish for cycling.


What do you suggest then? How or when should I add cardinals?


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## chinamansteve (Sep 13, 2010)

I just bought 10 cardinal tetras yesterday and added to my tank. So far they seem to be fine, pretty active schooling back and forth with the rummynose in my tank. My tank is about 6 weeks old now, got the water tested almost every week and it had 0 nitrite and 0 amonia. I will update you if anything goes wrong.

EDIT: Brought the water to the LFS today to test, and water is fine too, but the guy said my water is not acidic enough, and told me to try changing water every 2-3 weeks instead of every week..?


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## solarz (Aug 31, 2010)

chinamansteve said:


> I just bought 10 cardinal tetras yesterday and added to my tank. So far they seem to be fine, pretty active schooling back and forth with the rummynose in my tank. My tank is about 6 weeks old now, got the water tested almost every week and it had 0 nitrite and 0 amonia. I will update you if anything goes wrong.
> 
> EDIT: Brought the water to the LFS today to test, and water is fine too, but the guy said my water is not acidic enough, and told me to try changing water every 2-3 weeks instead of every week..?


Thanks! Hope all your cardinals do well!

How many fishes did you have before the cardinals? What is the size of your tank?


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## chinamansteve (Sep 13, 2010)

solarz said:


> Thanks! Hope all your cardinals do well!
> 
> How many fishes did you have before the cardinals? What is the size of your tank?


My tank is 55G. I have 10 rummynose, 6 pentazona (five banded) barbs, 2 plecos, and 16 guppy fry.

I heard cardinals are really sensitive to poor water quality, etc, so when I added them, I floated the bag in the tank for 30 mins, then added some of my tank water in the bag, floated another 15, then added more tank water in the bag for another 15 before I released the cardinals into the tank.


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## BettaBeats (Jan 14, 2010)

Its true. I believe that I added 8 microrasboras too soon after my tank cycled and it went through another cycle. I'd wait a bit seeing as your cycle 'just completed'

this will allow the bacteria to multiply. even for a small bioload, things can change quickly and any amount of ammonia or nitrite isn't good for fish, especially sensitive fish.


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## KhuliLoachFan (Mar 8, 2008)

I am amazed that 8 microrasboras could create enough bioload to actuall create a detectable cycle!

Any tank less than 9 months of continuous running, I wouldn't add tetras, without taking other steps. Maybe get a sponge from a more mature tank and float it in there for a week, and I'd feel safe.

Also, I'd be very strict about feeding a minimal amount of food for the first week. Just because there are more fish doesn't mean I can double the food I put in the next day. Move up the food to a normal feeding slowly over many days.

I have had TERRIBLE luck with Tetras when I add them to tanks running less than 9 months. I don't think test kits tell the whole story on tank maturity.

W


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## Chris S (Dec 19, 2007)

If you are worried about them causing a small cycle, just add them in 1 or 2 at a time over the course of a few weeks, then your filter will be able to slowly increase its capacity as your bioload increases.


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## gucci17 (Oct 11, 2007)

Chris S said:


> If you are worried about them causing a small cycle, just add them in 1 or 2 at a time over the course of a few weeks, then your filter will be able to slowly increase its capacity as your bioload increases.


solarz is aware of that but he/she mentioned they would like to take advantage of promotions that offer quantity discounts.


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## Chris S (Dec 19, 2007)

gucci17 said:


> solarz is aware of that but he/she mentioned they would like to take advantage of promotions that offer quantity discounts.


Ah, so I see!


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