Red Minor Tetra

Question
Hi
I have some Red Minor Tetras in my aquarium, but one of them can't close its' mouth. The mouth is always open. Could you tell me how this could have happened, please?

Thanks

Answer
Hi Kevin
Usually that means there's something stuck in their mouth.  See if there's anyway that you can look in it's mouth.  If there's nothing there then honestly I'm not sure what it is.  It may be it got dislocated some how.  Another possibility, I have a zebra danio, and when she's getting ready to lay eggs, she sits on the bottom with her mouth hanging open for awhile.  
If you can't see anything in it's mouth, try posting to another expert to see if someone else has had experience with that issue.  Good luck!

Christy