# Strange Fish Behaviour after water change...



## PeterandAnthony (Sep 4, 2008)

Just wondering if anyone can offer any ideas of a problem we have. We have a 3 foot tank and have around 8 Chiclids. We have had the tanks for over a year however when we do a water change 30% once a month (we have a large external Eheim filter that is fantastic ) the next day our fsh tend to all go to the top of the tank and it seems like they gasp for air. We put on an air stone during this time and within a day or two are swimming back to normal. Can anyone offer any reason why they hang out at the top of the tank seeming to gasp for air. Its just doesnt seem right?

Thanks in advance.


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## Big Vine (Feb 26, 2007)

Welcome to the forum!
I've moved your post over here where it will hopefully get more responses.

Are you adding some sort of tapwater conditioner/dechlorinator product when performing these water changes? It sounds an awful lot to me as though your fish are exhibiting symptoms of ammonia poisoning, which could be the combined result of chloramine in the tapwater and insufficient treatment (via dechlorinator products such as Seachem Prime) to get rid of it.

Please test your tapwater for ammonia, nitrAtes, and pH...and post your results here.
Also, please post your results for ammonia, nitrAtes and tankwater pH.

We'll get you some answers if you provide as much info. as possible! 
BV


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## duaneS (Aug 31, 2006)

I agree with big vine, and would add. 
After a month, there can be a large build up of metabolites that can change pH, alkalinity and many other water perameters, a 30% water change can be quite different from the newly added water in the tank, creating a bit of a shock to your fish and your bacterial colony. Bacteria can be quite sensitive to not only chorine, but this change and if large enough, their ability to osmoregulate could be comprimised. 
As an expiriment you may want to try a smaller (15-20% )weekly water change to see if the reaction of your tank inhabitants is as drastic.


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## duaneS (Aug 31, 2006)

Let me give you an example of a personal experience for the above statement.
I work at a large water producer, and a few years ago we allowed our filters to become biological. 
As part of my job, I was to determine the quanity of bacterial colonies in a small sample of the biological filter media.
I would take filter media, mix with water, and grow on agar in a petri dish. 
I 1st tried growth in RO water and found little, or no growth.
I next tried dechlorinated effluent water, which exhibited plenty of robust growth.
The efflunt water, was close to the normal constituent of water which passed threw the filters.
The RO was devoid of the minerals, which caused the bacteria to lyse, or, basically explode/implode because they could not handle the difference in water constituents.


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## Big Vine (Feb 26, 2007)

Thanks for adding that, Duane.
I completely missed this part, so I'm glad you pointed it out:



duaneS said:


> After a month...
> a 30% water change can be quite different from the newly added water in the tank, creating a bit of a shock to your fish and your bacterial colony


(somehow when I read the original post, I was thinking 30% weekly, when in fact the OP said monthly)

I would say that 8 cichlids in a 3-foot tank would definitely require a 30% water change at least once (if not twice) a week. But like Duane pointed out, you may wanna start off a little more gradual when you up the water changes...just so you don't end up shocking the fish.

Once you've worked your way up to a weekly 30% water change, your fish ought to be much happier.
BV


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## Robin (Sep 18, 2002)

Here's another scenario that can happen when you let too much time go by between water changes.

Ph will drop over time and that's not a huge problem in itself, the drop is gradual and the fish adjust. 
But here's where it can be a problem: if there is any ammonia present it will be virtually harmless at lower PH levels but when you add the new water _if that water has a higher PH _then the previously harmless ammonia suddenly becomes harmful and you may see the fish gasp at the surface and 'scratch around' as they react to the ammonia. Depending on how much ammonia there is it may even kill your fish outright.

So there's plenty of reasons to keep up with the weekly or at least bi-weekly partial water changes and if you've got a heavily stocked tank, or you tend to over-feed then those water changes are even more critical as water quality will deteriote faster. The filter you're using is great but there's no substitute for the benefits you get from frequent partial water changes.

Since the fish seem to have the symptoms when you do water changes I would also investigate everything you do for the water changes. Make sure the buckets and other water changeing equipement isn't being used for anything like washing the floors or car. Make sure you're using a good quality declorinator at the right dose. Are you adding anything to the tank when you do water changes?

Robin


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