Help! Cory With Breathing Difficulties!

[puppyduck]

Very worried.

Came upstairs to find my bandit cory Zorro breathing very very heavily.

He's the only one in the entire tank doing it and I dont want to lose another fish in 2 days.

They were fed at about 7.30, about 2 hours ago.

He seems active. Sort of. He swims about a bit and snuffles for food. Just as usual mostly.
But hes got such laboured breathing in looks scary.

PH is 7.0
20 gallon tank.
Ammonia is 0
Nitrite is 0
Nitrate is 5.0 ppm

Its 26 degrees in the tank and everyone else (all our other fish) are fine. He has no visible injuries and there's been no chemicals/treatments in the tank for over 2 weeks.

We do squish snails in the tank for the corys to nibble on but we've been told they wont eat any shell fragments so it cant be that. Our substrate is small gravel too so he couldnt have injured his barbels on that. They appear to be all present and correct.

Please help I'm so worried.

 

[black angel]

How much water do you change in a week as you seem to be overcrowded slightly to me?
Are you using a gravel vac. Plenty of oxygen or surface movement going on?

 

[puppyduck]

We gravel hoover usually about once a week, sometimes more often.

Last water change was Sunday. 10-20%. Occasionally more often.

Filter outlet pointing to surface. Bubble curtain. Plenty of surface movement.

Everyone in the tank was fine. And so was Zorro before we fed them. And my boyfriend gravel hoovered about an hour ago or so.

Oh yes, and he hasn't gone to the surface for air at all, so I'm assuming there's enough oxygen. It just seems so odd.

 

[WILDER]

Corys are prone to bacterial infections and can heavy breath with a bacterial infection.
Check the barbels to see if there short and thin.

 

[puppyduck]

Barbels are longish and quite chunky. We have other corys with longer barbels, but his were quite short when we bought him, and have since grown.

He also appears to be, er, pooping right now. So he's not bunged up. At least we dont think. He's in, er, mid flow right now.

EDIT: Have also seen bubbles coming out of his poopy parts. And he's taking a while to poop. Sign of constipation?

 

[WILDER]

What does his gills look like, just make sure also there no food stuck there.
I would issolate him if you can.

 

[puppyduck]

Or indigestion?

 

[WILDER]

Laboured breathing.
Bad water quality
Chemicals or meds
Parasite
Bacterial
Food stuck in there mouth

 

[puppyduck]

Just looked. Nothing seems to be stuck in his gills. Am leaving him in the dark for a while, see if he improves.

 

[WILDER]

He's not sounding good, fingers crossed and good luck.

 

[puppyduck]

Laboured breathing.
Water quality seems ok. No meds or chemicals for over 2 weeks.
So must be either food stuck in his mouth that we cant see (he had flake tonight) or parasitical or bacterial. But his barbels and colour seem good.

 

[WILDER]

Ok, hard to point things at times.
Just keep a close eye on him.