fish gasping for air

[Agent]

When I checked my tank this morning every fish was up top trying to get air, 6 of the smaller fish are dead & my 3 discus are also up top. I have cheked all the parameters with my test kit but everything appears normal. Yesterday I did the weekly water change but took out a large root which has been the feature of the tank for the last year, there was quite a bit of dirt around it so I vacuumed it up.
Any ideas before any more fish die?????????

[scott bowler]

check ammonia again and temp

[Agent]

Hi, Thanks for the quick response, temp is 29 & amonia is zero, have moved the discus into my spare tank for now, any other ideas??
Rob.

[scott bowler]

was the water you changed cold and aged ?did you check that water and how big was the water change ?temp seems fine good no ammonia

[scott bowler]

Agent what is your ph too

[Agent]

PH is 6.4, water temp when I change was 30, used the same method as I have done for a year, IE tap water, 1 bucked to 4 drops of prime water ager.
Rob...

[scott bowler]

some thing has shocked theses fish for them to drop , turn the light of leave them in the dark .how big is your tank ? do you use bucket al the time if so have the buckets been used for any thing else or just the fish . no one has cleaned some thing with the buckets and put some thing in it like soap or some thing

[Agent]

My tank is 220 litre 2x2x2 cube, the 3 buckets I use are dedicated for the fish tank & not used for any other purpose, this is wierd, just did 50% water change, the Tetras are no longer gaping at the top, dont think is was a bad batch of water as the same water was also used for the change in the spare tank & the discus I transfered to it appear to be ok & not up top...
Will monitor things with fingers crossed, thanks for your help.
Rob...

[scott bowler]

thats fine rob good luck mate like you said just keep an eye on them and cross your fingers

[Merrilyn]

Couple of things come to mind here -

Firstly, do you have an airstone in that tank, and have you been experiencing heat wave conditions like we are in Melbourne at the moment. It's possible the temp has risen through the day, making less oxygen available for the fish, and then overnight, any plants you have in the tank will stop producing oxygen and give off CO2, further reducing the amount of available oxygen.

Secondly, removing the driftwood from the tank may have exposed areas of the gravel that have released toxic gasses into the water.

Your plan of action now should be to give the tank a thorough gravel vac, and several changes of water to remove anything toxic that may still be in the tank.

Add some carbon to your filter, and let the water filter through carbon for a few days to remove any remaining toxins. If you don't have an airstone in the tankadd one now. Your two foot cube tank has a rather small surface area in relation to the volume of water. You need a lot of surface agitation to dissipate the CO2 and replace it with oxygen, especially at the high temperatures we have been experiencing this summer. Remember that warm water holds a lot less oxygen than cool water.

You should be able to transfer your fish back into their display tank after a few days, with no further problems.