Very Sick Cory

[Archiediamond]

Hey there,
I have three corys who have been living happily with half a dozen diamond tetras for several months with no problems. I'm super-vigilant about water quality and change it and/or test it every day - ammonia, nitrate and nitrite levels are all fine. But just over the last couple of days two of the corys have been acting kind of lethargic until this morning, one of them stopped moving at all - when I netted him to move him into a qaurantine tank he made only a feeble attempt to get away from the net. The other cory is a bit better (he rushes away when I look through the glass at him) and the third cory couldn't be happier! The tetras are all absolutely fine but I'm very confused! The sick corys were occassionally trying to bolt to the surface, would rest in the upper leaves of the aquarium plants or would just lay on the bottom of the tank, barely breathing. The tank is 37 litres (not sure what that is in gallons, sorry) and I don't add anything to it, just a dechlorinator when I change the water. Absolutely nothing has changed in their water, they have no new tankmates and their diet is the same as always.

Does anyone have any idea what could be wrong with them?!!!

Thanks so much in advance.

 

[WILDER]

Corys are very suspectable to bacterial infections and they heavy breath with bacterial infections as well, can you issolate the fish, if not add a bacterial med to the tank, are they laying to one side, check the barbels to see if they have gone shorter or thinner.
I gravel vac my tanks twice a week as bottom feeders are prone to bacterial infections from the gravel or sand as if they eat rotten food it causes desease.

Also can we take a look at your stats in ammonia,nitrite,nitrate,and ph.

 

[Archiediamond]

Ammonia nitrates and nitrites are zero, and the Ph is 7. I do a partial water change every day and I vaccum the gravel at the same time - having said that, there is a big bit of teak close to the back of the tank (which the corys are currently hiding behind) with lots of plants behind it so I can't vaccum back there. I'm wondering if there's been a build-up of waste back there and the corys have picked something up from that.
The sickest one actually died a couple of hours ago (very sad now) and the other two are sitting around, looking listless, except when I try to net them, at which point they go crazy and hide! Isolating them would mean basically tearing my tank apart so I'm going to have to wait until they venture out the front again, as trying to catch them is stressing my tetras.

I'm so confused! I've really tried hard to keep this tank in perfect condition...

 

[Miss Wiggle]

correct me if i'm wrong someone but shouldn't there be SOME nitrates in the tank? I know levels too high can damage the fish, could to low a level damage them as well? Not sure but just a thought.

And yeah I'd try n get that gravel vac in there mate, I vac around my plants, if I uproot one I just re-plant it.

 

[WILDER]

Yes i would get the vac out, my cory like to hide near the filter and i move it to clean there as you will be surprised how much muck gets there, you can get bad bacteria pockets, that why is so important to give the gravel or sand a stir at least once a week.
You will need a bacteria med for them, good luck.

 

[Archiediamond]

My only concern is that all the fish like to hide behind the piece of wood when I do the water change but I guess I'm going to have to toughen up and stop babying them! Bring on the vac...thanks guys!

 

[Miss Wiggle]

My only concern is that all the fish like to hide behind the piece of wood when I do the water change but I guess I'm going to have to toughen up and stop babying them! Bring on the vac...thanks guys!

move the bit of wood somewhere else in the tank, then they can still hide behind it and you can vac there then move it back. Just like doing your living room, move the furniture and do underneath it

 

[Archiediamond]

Right you are...I'm such a coward, I fret about squashing one of them when I move the wood! They're probably much tougher than I give them credit for...though I've just stressed them to hell and back, catching the corys (one of whom now has a fluffy white growth above one of his eyes) to quarantine them.

 

[WILDER]

If you have a fluffy white growth above his eye is sounds like columnaris, you will need myxazin and primafix.