To Breath or not to breath (air)...

Crazie.Eddie · Post by **Crazie.Eddie** » 21 Mar 2004, 10:51

This is going to be a stupid question. I heard that Cories can breath air, like labarynth fish (bettas, gouramis, etc.). Is this true?

Chrysichthys · Post by **Chrysichthys** » 21 Mar 2004, 16:36

Yes it's true, after a fashion. They dart to the surface and swallow air. Oxygen absorption occurs in the digestive tract.

They don't have a specialised labyrinth organ.

Crazie.Eddie · Post by **Crazie.Eddie** » 21 Mar 2004, 20:42

Are they actual air breathers and if so, could they drown without regular air? Or do they only dart to the surface for air when the DO (Dissolved O2) is low in the water?

Post by **Silurus** » 21 Mar 2004, 20:56

They seem to do it regardless of the DO level in the water. Of course, this becomes more frequent when the DO is low.

Crazie.Eddie · Post by **Crazie.Eddie** » 21 Mar 2004, 21:27

If they don't have access to surface air, will they drown?

Post by **Silurus** » 22 Mar 2004, 01:36

I don't think their gills are so poorly-developed like clariids that they would drown without access to atmospheric oxygen.

pturley · Post by **pturley** » 22 Mar 2004, 15:06

There were several studies conducted on this topic. (late '70s early 80s if I remember correctly)

Don't have the refs. handy (I'm at work) but could likely find them. I'll post them later. At least one of the papers focused on the specific functions of various hemoglobins in the blood of various air breathing fishes (Clarias and Corydoras included) and how the blood chemistry adjusted to the increased uptake of CO2 associated with atmospheric air.

Corydoras will actually loose equilibrium when denied access to atmospheric air. So the gut regeons that are typically gas filled aid in the function of the swimbladder.

In waters with marginal or low Dissolved Oxygen (DO), or high concentrations of Hydrogen Sulfide (HS) gas (IE: a swamp, typical habitat for many Corydoras spp. ), they are oblogate air breathers. Or, yes they will asphyxiate.

kateswan · Post by **kateswan** » 12 Apr 2004, 13:44

Here's a good story, with perhaps some bearing on this topic --

While vacuuming tanks and cleaning up, my daughter started
yelling for my help. An albino aeneus cory, nearly an inch long,
was swimming up and down inside the tube under the powerhead
connected to an undergravel filter.

Every time we removed the powerhead, the little guy disappeared
into the nether regions. We finally held the powerhead in place
for suction, and when the little guy appeared again, slid the whole
tube w/powerhead still attached at a slant, and spilled him out
into the tank.

He acted very disoriented and a little stunned, but quickly made
friends with the other albinos. A quick count revealed he was
not one of our regulars -- and there was *no* way he could have
gotten under the powerhead into the tube.

That leaves growing up in the undergravel filter! He must have
either hatched and slithered down between the gravel, or
the egg got sucked into the gravel.

Anybody else ever seen something like this happen?

He wouldn't have had access to surface oxygen the entire time.

Kathy S