# Fish keep hiding during CO2/Light period?



## DRG93 (4 Feb 2016)

Hi all,

I am currently facing an issue of my fish remaining hidden at the back of the tank during the CO2 and Light period from 11am-7pm. I don't think it's the light brightness as some forums suggest as I keep it on a pretty dim setting (lower light intensity than the fish shop I purchased the fish from anyway!).

I know that injecting CO2 can cause the pH to drop so would it be possible that the pH drop is causing the fish to become lethargic and 'hover' at the back of the tank. They don't sit on the substrate, they seem to just float in one space, in the dark areas at the back of the tank.

The temperature of the water is set at 25C (approx. 77F) and can fluctuate ever so slightly 24.5-25.5C. I don't think it's the temperature of the water either. In addition to this, when the lights are off and the CO2 is off, the fish do occasionally come out of hiding regularly but not as often as normal.

I do not have any test kits to test pH or KH or anything like that. The tank is fully cycled (as in, it's been set up for months, with an overpowered filter) and I have been keeping fish and plants for years. It's just odd behaviour that I have recently experienced. I'm not sure if it's been going on for longer that I think as I work all day weekdays and I'm barely home at the weekends so it could be an issue that's being going on for a while.

Filter flow is quite strong but the fish I keep are *Neon *and *Ember Tetras - *I'm sure they love good flow. Shrimps are acting fine. Also, my oto's and pygmy corys do hide as well.

Shall I test my water and see what I get?

It's weird because I haven't changed my processes - i.e. EI dose, feed the same food, water changes weekly etc. I can't pinpoint the issue at all.

Any help would be great,
Thanks,
Dan


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## philipraposo1982 (4 Feb 2016)

Have you done a big rescape or anything recently?  Been in the tank alot?

Maybe dial down the co2 a bit or don't run it for a day.

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## darren636 (4 Feb 2016)

Sounds like co2 toxicity.


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## jagillham (4 Feb 2016)

I find my neons / cardinals are shy. They hover under cover whereas the rummys are about swimming.


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## philipraposo1982 (4 Feb 2016)

My cardinals always hid and its perfectly natural behavior.  I moved on from keeping them for this reason.  In heavily planted tanks with tons of cover, most small fish species will take cover.  They don't know that there isn't no predators around the corner.

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## alto (5 Feb 2016)

DRG93 said:


> fish remaining hidden at the back of the tank during the CO2 and Light period from 11am-7pm.


What are fish doing outside these times?
(assuming there's sufficient ambient light to observe behaviour)



DRG93 said:


> *Neon *and *Ember Tetras - *I'm sure they love good flow.


not really - these are stream & tributary fish (think slow flow) rather than main river fish, so try turning down the filter to see what happens



DRG93 said:


> the fish to become lethargic and 'hover' at the back of the tank.


As noted above, check CO2 levels - I watch a surprising # of high tech tank videos where fish are not as active as "normal" & always suspect CO2 toxicity
Try decreasing CO2 levels for 3-4 days & observe any changes



DRG93 said:


> It's weird because I haven't changed my processes


have you added any new fish or plants?



DRG93 said:


> the fish do occasionally come out of hiding regularly but not as often as normal.


this suggests stress or ill to me -  you might treat for external parasites if none of the others changes improve activity

What happens when you feed?




DRG93 said:


> Shrimps are acting fine.


type of shrimp?
breeding?
If shrimp are active etc then water parameters would seem to be less of issue ...
- back to fish feeling under the weather  (I treat with formalin as it's very effective against a broad spectrum of external parasites (& the dye based meds are not really as benign as presented) but make sure you've done your research before using any meds: note don't medicate for 24 hours if you see fresh shrimp moults)
- or fish are more sensitive to low oxygen levels or high CO2 levels (both or one may be occurring) 

I have wild green neons in one tank - as soon as they feel the vibrations of approaching predators they disappear into the plants - sit quietly in a chair & they are quick to reappear & go about their business ... I'm going to try adding some TR black phantoms & see whose habits change


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## DRG93 (5 Feb 2016)

Thanks for all the responses - the main cause of action I have taken is that I have dialled down my  CO2 slightly and will monitor the fish as much as I can for the next few days. The surface agitation of the water is good, so there's plenty of Oxygen being dissolved into the water. I'm guessing that if it was Oxygen deprivation, they would be seen at the surface of the water trying to get air?

Does anyone know of any fast-flow loving fish? When I say fast, I don't mean it's like a tsunami in the tank but that the plants are gently swaying (ever so slightly).

Nope no new plants.

Outside of this lighting and CO2 period, the fish do tend to come out a little bit more but it still isn't 'normal', most of the time they still remain at the back of the tank and poke themselves out every now and then.

I did also turn down the filter flow and I have noticed that the Neons and Embers are starting to come out a bit more but they aren't swimming around, just hovering in one area together.

I'll monitor the situation and update accordingly.

Thanks!


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## Dr Mike Oxgreen (5 Feb 2016)

You may wish to have a browse of my "What's wrong with my chili rasboras" thread, in which I had similar behavioural problems. My fish were nervous and restless rather than sluggish, although they were hiding in corners as well.

In summary, I think I may have solved the problem by:

Replacing the lily pipe with a spray bar for a more diffused water flow.
Adding quite a few more of the same type of fish.
Installing an LED controller to ramp the lights on and off.
Allowing floating plants (hornwort, in my case) to run riot and create a lot more surface cover.
Oh, and of course you should make a shoal of rubber decoy neons and ember tetras to encourage the real fish to come out. That goes without saying!


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## DRG93 (5 Feb 2016)

Dr Mike Oxgreen said:


> Replacing the lily pipe with a spray bar for a more diffused water flow.


I do have a spare spray bar so I might give that a go, see if that affects them positively.


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## PARAGUAY (5 Feb 2016)

I just watched Tom Barr video again for the umpteenth time,Troi put it back for newcomers,and I think there may be a clue there for you,when you see fish in shops they are often in empty fish only tanks so they naturally are in the open and show shoaling behaviour in the home tank they might not do this because they are usually in small numbers and in Toms big tanks they are in huge numbers feel confident enough not to hide,also the room is busy,people about making noise Tom disturbing the tanks hands in its what the fish are used to.Also he feeds them they come up robust for food .Providing it's not flow or co2 related you could add some top area dither fish like danios and keep them hungry for a few days then try tiny,tiny feeds four or five times a day soon they will seek open areas watching for food.Dont be to quiet around the tank.The reason they may have changed behaviour in the first lace may just be down to flow too strong and they merely find quiet spots


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## Wisey (5 Feb 2016)

My fish, Corys, Ottos and Ember Tetras also act like this, but will come out to the more open front area more often if the filter is off or there is food to be had. They do tend to be more adventurous in the dark or just ambient light. I figure it is a combination of the flow (maybe the CO2 although they are not gasping) and the bright light in an open area. My plant growth is not dense due to issues with the tank in the last few months, so they seem to sit in the low level plants at the back and behind the wood where there is less flow.

At the moment my foreground area has chunks of dragon stone sat in it with Anubias and Microsorum tied to it in preparation for a rescape and with that area having more cover, the fish are out there way more often even with the lights, CO2 and high flow. I guess they just feel safer.


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## FIsh i (5 Feb 2016)

Just added 15 embers and 10 celestial danios (gr8 fish) to my tank, no shyness quite planted with open space also shoaling well together- could be a number game


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## xim (5 Feb 2016)

Is the amount of fish in your tank the same as before the behaviour occurs ?
If it's lower, I would try adding more fish.


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## alto (5 Feb 2016)

DRG93 said:


> Does anyone know of any fast-flow loving fish? When I say fast, I don't mean it's like a tsunami in the tank but that the plants are gently swaying (ever so slightly).


Your flow may be just fine - given this description
If you drop fine fish food in the tank it's easy to see flow patterns - I use minced frozen food, if flake, you'll want to pre-soak for a few minutes so that it's no longer floating


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## DRG93 (5 Feb 2016)

*UPDATE*:

I have switched to a spray bar and they seem to be coming out from hiding more often than normal. In fact, the past ten minutes I've seen more of them than I have done for the past ten weeks! 

In total I have dialled down CO2 slightly and replaced my output with a spray bar. 

Also.... I've got more fish than I thought! Haha! 

Thanks for everyone's tips, I'll monitor the tank and update once again if the hiding continues


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## zozo (5 Feb 2016)

DRG93 said:


> Filter flow is quite strong



Did you ever try to do something about that and see the results?? 
http://www.ukaps.org/forum/threads/shy-embers.37412/#post-403922

Ember are quite shy by nature, they are tiny and very low at the food chain. I started out with a school of 15 embers only at first for a few months.
I noticed them very sensitive to flow and always gather in one specific corner, changing the flow direction they replaced the corner with another place. What it excactly is what they prefer i do not know, i do know they don't like it to much.

i resently discovered the term Dither fish, i didn't know it before.. Anyway i noticed a very positive effect on the embers after adding a little school of Black Tetras, this was purely by chance, never had black tetras before. These Tetra's are much more boisterous and less shy, since they are together the Embers react on the Black tetras behaivor.. The blacks spot food and race towards it and the embers follow.. The blacks even see my hand in the tank as possible foodsource whirling up food and come towards it, the embers are with them. Before that without the blacks if i moved in front of the tank they were gone and dived into the opposite corner.. . So using a more boisterious dither fish with which they can school together does have positive effect on shy ember behaivor. 

Two shy spieces together only trigger eachother to stay shy..  Something logic actualy to think about..


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## fleetEWD (5 Feb 2016)

I'm in the same boat. 10 ember tetra and very open tank. Lights off and they all explore tank in non schooling patterns. as soon as lights on it's of to the most planted corner with even some burying themselves in my hydrocotyle tripartita! im off to MA tomorrow t look for some brave guys to set a good example.


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## darren636 (5 Feb 2016)

fleetEWD said:


> I'm in the same boat. 10 ember tetra and very open tank. Lights off and they all explore tank in non schooling patterns. as soon as lights on it's of to the most planted corner with even some burying themselves in my hydrocotyle tripartita! im off to MA tomorrow t look for some brave guys to set a good example.


This is exactly why I gave up with high tech.


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## fleetEWD (6 Feb 2016)

Well i went out today and got six spotted rasboras and it seems to have resolved the issues. No more huddles in the corner as of yet. Lets see how they fare after water change sunday.


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## DRG93 (8 Feb 2016)

*Another Update:*

Everything seems to be OK now. The fish swim around and school occasionally whether it be lights on or lights off. The CO2 is at the optimum level for the tank. The only major difference that I have made is switching out the lily outflow pipe with a spray bar to disperse the flow so that's distributed evenly across the surface of the tank. I think the flow was the issue - maybe it was too strong? Either way, it's all OK now and all fish are acting well, normally!


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