Black skirt tetra needs help

[Dooner]

I have a well-planted 40 gallon community tank with 5 black skirt tetras, 7 neons, 3 bala sharks and a corey. It's been very stable and healthy for weeks, but now one of the black skirts is having a problem- his mouth is stuck wide open. I noticed it last night, and in addition to this jaw problem he had a long hair like excretment hanging from his anus, (which this morning is no longer there)...I tried feeding them today and all the other fish were fine, but the poor blackskirt couldn't get any food down (cuz he couldn't close his mouth). Is this a parasite? Some sort of reverse lockjaw? Please help.

 

[Angel Lady]

No I dont think it is a parasite. Could he by any chance have a gravel in his mouth or something??? And one more thing cories are a schooling fish they need to be kept with three or more.

 

[WILDER]

If the mouth is stuck wide open and there is nothing stuck in it, there is nothing to be done i'm afraid, what colour was the hair thingy hanging out of the anus.

 

[Dooner]

It was white and long and thin... at first it actually looked like a shred of his pelvic fins, but upon second look it definitely wasn't that.
I also originally thought it was something lodged in his throat...either a piece of gravel or a piece of one of the sinking pellets i put in there for my corey...the silvers often play with those...But my gravel is bright blue and I don't see any of that in his throat (I can see right down in there), and a pellet would have broken down by now...he's been like this for at least 12 hours.
I am fairly certain that he is going to die, my bigger concern now is...Is this a mechanical problem with the one fish, or is it all possible that it's something that can affect the rest of the tank? Should I set up a hospital tank?

Thanks for responding so quickly...I'm really impressed with this forum.

 

[WILDER]

I bought some harlequins and the next day some of them was swimming round with the mouths wide open they couldn't shut there mouth, there is no cure just do a few daily water changes, it didn't effect any other type of fish what they had, the long stringy thing could of been poo, as long stringy white poo can be a bacteria infection or internal parasites, or constipation.