White 'stuff' hanging out of Corydoras mouth/gills

[DrawsWithLight]

Evening All!

This afternoon I was doing a water change on the tank and noticed some white 'stuff/gunk' hanging out of one of my corydoras gills. Weirdly the white 'stuff' disappeared then reappeared on the other gill and then the mouth. The fish didn't appear to be in distress and was swimming normally with its other tankmates. Later on, after finishing the water change, I noticed the white 'stuff' on the gravel. It then struck me that I'd seen something similar several weeks ago when cleaning the tank. The Cory looks fine now with no signs of the 'stuff'!

Any ideas anybody? (NB the gravel is rounded and not sharp and I have a sand area centrally in the tank)

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[VikingMummy2015]

It was trying to feed on whatever it is. If you watch them eating bloodworms you’ll see it sliding in and out their gills like spaghetti.
Picture isn’t easy to get a close up view on (for future pics, delete the square brackets at the start and end with the url text, and that will embed the photo rather than linking to it elsewhere. It almost looks like skeleton; have you done a head count recently?

[DrawsWithLight]

Can you view the pics better now? That's reassuring that it's not a problem with the Cory, but not very reassuring that it's something else that's dead?! I've not done a headcount, I've got 23 tetras so they're tricky to count up! I'll try and photograph them to do a head count tomorrow! The rest of the occupants are snails and shrimp.

[plankton]

Try to get whatever it is out of the tank so you can determine what it actually is.
It does look a bit like fish remains......?
As long as it isn't stuck in the fish it should be ok.
Do you have an area of sand for them to feed on? It's quite weird (but cute) to watch then filtering sand through their gills.....

[DrawsWithLight]

I thought it might have been shrimp remains as I couldn't find all the Amanos over the weekend but they have since made a re-appearance. All other species are present but counting the teras is challenging! I'm pretty confident I've not lost any recently as I do have a good nosy around the tank several times a day and I'm sure I would have spotted a dead one?! I didn't get the white stuff out of the tank, by the time I'd photographed it and got around to it, it had disappeared. The last time I found it though I 'fished' it out and it was the consistency of snot!

I have an area of sand but I've not seen the Corys filter it through their gills, perhaps it's not fine enough?

[plankton]

It could be shed shrimp carapace, but if it's that consistancy it must be quite old.....the amanos should eat it for the calcium.