Peppers Floating?

[Harlequins]

i bought some peppered cories a week ago,after lfs caught 3 of them,one went upside down,i pointed this out and he gave me another one but said he didn't want to stress the other cories so left the upside down one i the bag.
I took the 4 cories home all seem ok-ish,until a few days ago one poorly one hardly moved,i put him in a net away from the others,he has a curved spine anyway but just kept floating around...this morning i thought he was dead but wasn't i could see his gills moving even though he was lying on his side,i thought i would put him out of his misery,rightely or wrongly i made up some ice cold water and sadly put him in there,half hour later i was checking to see if he'd gone and he was still breathing!!! i felt awful hurting this little cory! anyway i put him back into some tank water and he's still lying on his side gills going,i haven't the heart to try to euthunise him again.
Now 2 of the other peppers are starting to float around the tank,they do swim and root around the bottom but i usually find them near the top by the water edge just lying there?
They were quite dark in colour when i got them.
All the other fish in my profile are fine.,although i'm now concerned they might pass something on.

Ammonia 0,nitrite 0,nitrate 30(tap 10),ph 7.8, temp 25.3
rena 216 litre,filters x2 tetratec ex 700 and ex 1200.

Is it normal for peppered cories to hang around the top?

 

[nmonks]

It isn't normal for any Corydoras species to spend much time at the surface. Schools of a few of the "dwarf" species sometimes swim about in midwater (e.g., Corydoras habrosus) but mostly they're strictly benthic fish.

The most common reason they stay at the top of the tank is poor water quality. It is critically important to ensure the aquarium has good water circulation. Poor filtration systems may move water at the top well enough, but do very little for the layer of water at the bottom. Since that's where these catfish live, stagnant water at the bottom of the tank is dangerous.

The best filters for tanks with catfish are those that either draw water through the substrate (like undergravel filters) or filters with inlets close to the bottom (like canister filters). Check that the filter is adequate to the size of the tank, and that it is offering good circulation. Does flake put on the bottom just sit there, or is it quickly whooshed along?

Do also remember most Corydoras species come from relatively cool, shallow streams. For Corydoras paleatus, optimal water temperature is about 20-24 degrees C. Water depth should be around 20-30 cm, and no more than 40 cm for adults. In deeper tanks, use other genera, such as Brochis.

Cheers, Neale

 

[Harlequins]

They are not intentionally staying at the top,they seem to float up there?

There's plenty of filtration, with 2 externals and plenty of movement in the water from the flow bars and air bubbler,my other cories- C.Trilineatus are fine,

Now they're lying on the bottom sideways if i disturb them them swim away like normal?? they're definately not acting right has after they swim away its like they float to the top.

Someone please help!

 

[crazychris]

Doesn't sound normal at all yet you say they scavenge normally sometimes still. Very odd indeed. Cories shouldn't lie on their side at all like Botia loaches sometimes do. They shouldn't have fast breathing or be floating up to the top either. My two albinos sometimes swim up and down the glass to and from the top but are only playing really. As you've only had them a week and you say they were like that when you first got them why not ring the shop and ask if you can take them back? Or go and see what the others left in their tank are like and speak to the shop manager/owner then?

 

[Harlequins]

I wasn't happy with these cories so i took them back,sad to see them go but they weren't acting normal,anyway the lfs sais they haven't had any problems with the others(has if they would say),they tested my water and said would i like some more but i refused and they gave me a credit note for the cories.

 

[Dogson]

I had something similar to this happen to me when I first setup my tank! I started with 6 peppered cories and one by one they died. I did a fishless cycle for over a month and added them in.
I got down to one peppered cory which just seemed unexplained as all my other fish were fine. I chose not to add anymore for a while until a few weeks ago I added 3 more tankmates for the loaner and they have been fine. This could be down to Tank maturity and if indeed there is enough scavenger food for them?
don't be put off from them by your experience they're great little fish but I would say they are a little more sesitive than people say and would prefer a mature tank with plenty of food available.