Help: Gill worm on a red zebra?

Hi,

I have a Red Zebra Malawi Cichlid which has a black string about an inch
long dangling out of one gill. Both gills appear to be red and swollen.
All the gill worm descriptions I was able to find describe white/green
worms which are barely measured in millimeters... this seems not be fit
the description.

If anyone has any idea what this is, it'd be helpful in choosing the right
medication. The added complication is that this Cichlid is holding (for
at least 2 weeks now), together with another one, and both are in a
sectioned-off area of the main tank. I don't know if I should wait for it
to release the babies prior to attempting treatment and quarantine...

Thanks for any help,
Akom