# My fish keep going to the surface - only at night



## shannon767 (Oct 9, 2016)

Something strange has been going on the last couple of weeks. I have noticed that my fish start hovering at the surface, gasping for breath, but only at night. And not every night, either, maybe 2 or 3 times a week. Those not at the surface appear agitated. 

The obvious answer is lack of oxygen, but I no longer use CO2, so I am not clear on how/why this would happen. I increase the water flow and pump some air in using a surface skimmer and everyone ends up settling down, and they are still okay in the morning. Anyone have any ideas for me? 

Details:
20 gallon planted tank (med-heavily planted)
9 green neon tetras
5 glow light tetras
5 ember tetras
2 endlers
1 mystery snail
3 nerite snails 
100+ cherry shrimp

I recently read the Walstad book and decided to go with her strategy, so I took out the DIY CO2 and haven't done a water change in 4-5 weeks. Water params are normal: 0, 0, <10

I just trimmed the plants down last weekend, they are growing like crazy! Way faster than when I was doing CO2 and weekly water changes. 

This new method and the pennywort are the two new things going on in the tank. 

Here's a pic of my tank. I know it looks messy, the plants are growing like crazy and I'm trying to figure out what I want to do with them. 

Thanks in advance for any advice you can give me!











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## BettaBettas (Aug 21, 2016)

do you keep your co2 on at night? I suggest turning it off 1 hour before lights go out


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## natemcnutty (May 26, 2016)

BettaBettas said:


> do you keep your co2 on at night? I suggest turning it off 1 hour before lights go out


They said they don't use CO2 anymore a couple of times 
@shannon767, are you doing the surface skimmer all the time, or only when they are at the surface? Plants do consume oxygen when lights go off, but I can't imagine enough to cause this.


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## shannon767 (Oct 9, 2016)

I run the skimmer all the time, but it doesn't do much normally. What I do is raise it out of the water enough that it only sucks in air instead of water, thus creating lots of air bubbles. I use a Finnex Planted+ 24/7 light, and it is always on the same cycle. It doesn't get fully dark until closer to midnight, but I see them at the surface around 8:00 pm. 

I feel the same way you do. I know that plants consume oxygen, but they also release it, and I have no idea why they would suddenly be consuming so much that it affects the fish. It's really weird. 


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## sdwindansea (Oct 28, 2016)

Even though you are not running CO2 you have a drop checker and it appears green to me (although I could be color blind). Is that a current tank picture? Maybe there is too much CO2 in your tank that isn't being consumed as the lights ramp down.


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## clownplanted (Mar 3, 2017)

sdwindansea said:


> Even though you are not running CO2 you have a drop checker and it appears green to me (although I could be color blind). Is that a current tank picture? Maybe there is too much CO2 in your tank that isn't being consumed as the lights ramp down.


Good catch as I see the same thing appears green. Was the pic taken before you turned off co2 all together??


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## That fish guy (Mar 26, 2017)

As far as i know fishes usually stay at the surface when they are resting or sleeping!


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## shannon767 (Oct 9, 2016)

I haven't added CO2 for six+ weeks. The checker is green, which SHOULD indicate an acceptable level of CO2. 


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## clownplanted (Mar 3, 2017)

shannon767 said:


> I haven't added CO2 for six+ weeks. The checker is green, which SHOULD indicate an acceptable level of CO2.
> 
> 
> Sent from my iPad using Tapatalk




If you are not injecting co2 how is it green? That means you should be right around 30ppm of co2. If the color is green during the day then at night when plants stop photosynthesizing what color does the drop checker go? Just curious how it's even green if no co2. Should be blue if not injecting. 


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Mine is a lighter green during the day when co2 is on then after its off a couple hours later it's a noticeable blue. 

One hour after co2 is off









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## onlycrimson (Sep 7, 2010)

I would try setting an air pump to run at night and see if that changes anything.


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## shannon767 (Oct 9, 2016)

onlycrimson said:


> I would try setting an air pump to run at night and see if that changes anything.




Thanks! I bought one yesterday. We'll see how it goes. They seem happy so far. 


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## hector.hinojosa. (Oct 24, 2016)

Hmmmm...This happened to me once when I had lots of guppys when I would turn off air stone off. Maybe need air pump. I now have 20 gallon long with no air pump lots of tetras doing fine.







No problems running eheim 150 classic canister and aqua clear 30 for extra bacteria rings.

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