What does it mean when red stuff is coming out of the corner of a gerbils eye?

Not quite sure what you're asking, but rodents produce a red mucus called porphyrin that scares many owners into thinking they are bleeding from their eyes or nose. This can be caused by illnesses such as an upper respiratory infection, which can be deadly if it goes untreated; or something as simple as a stressor in the environment, such as using the wrong bedding (pine and cedar are NOT recommended for any rodent) or even just adjusting to new smells in the environment.

If your gerbil develops this, make sure you are using proper bedding (aspen and Carefresh are highly recommended), and be sure the gerbil is not having labored breathing (rapidly heaving sides) or clogged passages (if you hold them up to your ear, they would make a clicking sound as they try to breathe), as these are signs of a respiratory infection. This can be treated over the counter using doxycycline, which should be available at local pet stores in the bird section--use dose for small birds. It is also advisable to take your gerbil to the vet, as they will be able to give you a better diagnosis and better medication for treatment.