# All fish swimming at the top



## fishbut (Nov 22, 2010)

Hello

Recently, most of the fish in my aqarium have started to swim at a weird angle at the top of the tank, almost with their mouths sticking out of the water. I have tested the water twice over the past few days and it is perfect. It's 450 litre tank and the fish swimming at the top are the buenos aires tetras (8 of these) and the zebra danios (20 of these), also the corys (5 peppered and 2 albino) keep diving to the top for air on a regular basis... this is only a recent thing, none of these fish done this up until about a 3 weeks ago. It seemed to start when we put a our common pleco in (he is about a foot long). Another issue we have it that the sand is turning black, I have read up about this and have churned the sand as I read it helps which it has.. it just seems the tank is falling to bits... a few weeks ago the fish were active and thriving now they all seem lethargic and hardly move...

any help would be greatly appreciated..


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## WH2O (May 15, 2010)

low oxygen levels?


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## sik80 (Mar 16, 2010)

fishbut said:


> Hello
> 
> Recently, most of the fish in my aqarium have started to swim at a weird angle at the top of the tank, almost with their mouths sticking out of the water. I have tested the water twice over the past few days and it is perfect. It's 450 litre tank and the fish swimming at the top are the buenos aires tetras (8 of these) and the zebra danios (20 of these), also the corys (5 peppered and 2 albino) keep diving to the top for air on a regular basis... this is only a recent thing, none of these fish done this up until about a 3 weeks ago. It seemed to start when we put a our common pleco in (he is about a foot long). Another issue we have it that the sand is turning black, I have read up about this and have churned the sand as I read it helps which it has.. it just seems the tank is falling to bits... a few weeks ago the fish were active and thriving now they all seem lethargic and hardly move...
> 
> any help would be greatly appreciated..


few questions - what are you testing the water with? liquid test kit is best. What are your results for ammonia, nitrite and nitrates?

sand can compact and trap bubbles of hydrogen sulphide gas as bacteria break down organic material without oxygen. When you stirred the sand did bubbles come up from it? Hydrogen sulphide has a rotten eggs smell - did you notice this at all?


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## SilersAngryMeow (Mar 2, 2010)

sik80 said:


> sand can compact and trap bubbles of hydrogen sulphide gas as bacteria break down organic material without oxygen. When you stirred the sand did bubbles come up from it? Hydrogen sulphide has a rotten eggs smell - did you notice this at all?


I was thinking this as well. I've never had it happen in my tank, but I read that if this happens, you'll see dead fish rather than gasping fish.  I don't think I would stir up the sand.

Fishbut, is the temperature in your tank okay? Filter running okay?


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## willow (Sep 9, 2006)

hi
i'd say do more water changes and more regualr stirring of the sand is needed too.


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## WH2O (May 15, 2010)

did you test for ammonia? Ammonia might have burned the gills.


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## Byron (Mar 7, 2009)

Everyone so far has good suggestions. Until you find out the source, daily water changes opf 50% are strongly advised. Fish "gasping" which is clearly what this is means something toxic is in the water--it may be excessive CO2 with low oxygen, gas from the substrate, ammonia or nitrite, very high nitrate, very low (sudden) pH, some poisonous substance in the water--any of these will cause the symptoms you mention. A daily 50%-70% water change with a good conditioner will keep whatever it is at low levels until the source is identified.


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