hanging around the top...?

[sammigold]

Hi,

have noticed one or two of my cory sterbais swimming up to the top and sort of floating (not on their backs!!!) they put their little mouth up and impart little bubbles onto the surface of the water...

I am worried that there is something wrong... the rest are ok. (have 12)
did a water change last night and only one seemed to do it again this afternoon.

I thought it might be a normal thing as I have noticed them going up and down like mad etc.. but my man is a bit worried as these two were sort of hovering more at the top.... (they do go back to the bottom but spend a bit longer up top than the others ever do)

any ideas???

[sammigold]

I have lost two of my sterbais. They have no external symptoms other than possibly being a little red around the gill area..(but nothing that I thought was suspicious)

They were (I am assuming that the two dead ones are the same two that were hanging at the top more than normal, its hard because they all look the same!)
displaying this behaviour for about two weeks.. at first we thought it may be normal but then we decided not.
We have performed extra water changes...
checked all the parameters.....
nil ammonia,
nil nitrites,
nitrates around 10,
ph 7 temp 26 gh 12 kh 3-4
they have been in the same tank for the last 3 or 4 months. they only have guppies as tankmates.
No new fish have been added only new fish are fry that have been born to the guppys in the tank.

They are fed flake, pellets for bottom feeders, and zucchini and cucumber.

They seem me to be not as active within the colony as they used to be but it could be because they have settled into their situation.
I am at a loss as to what may be the problem, am treating the tank with Pimafix as of last night. Lost the first one 2 nights ago and the 2nd one today.
Does anyone have any suggestions as to what I may do?

Currently am hoping that it was just a coincidence that I lost two so close to each other and am hoping/assuming that it was the two that were acting weird and hoping that It was just those two affected.

thanks in advance.
sammi

thanks in advance...

[nicholas76]

you got an air stone happening mate?

[sammigold]

Have now... :-) however dont think it is making much difference....

[nicholas76]

you losing more? others showing same signs mate?

[sammigold]

They are not hanging around the top.... they just look a little "dull" and fins of a couple seem a bit clamped.(not totally clamped just not upright and bright looking)

I dont know if I am being paranoid because I lost two so quickly...but Vic seems to be worried too so Its not just me.

Tonight we just did a 75% water change as the only thing done recently was take 2 rocks out and clean them of algae using bleach..(I am worried that they had traces of bleach still on them..but dont want to point any fingers) rocks are out now and huge water change done, cleaned filter sponge and with the airstone running am hoping that they improve over the night... they are just sitting around at the moment so I guess I just have to give it some time.
They dont look like they are going to die but then neither did the other two... I am totally paranoid now... Thing is normally it would be the guppies to go first from previous experience and my gups are totally happy and healthy so I am stumped...