More Of A Question Than A Post Problem

[BaylorPerez]

Within my danios i have noticed one of them to be brighter blue than the others that i have, i am unsure of what this is, but it looks like it happened after the red gills seemed to have taken effect on ONLY the danios. My tetras are just fine. Oddly enough, even with adding the melafix, the red gills have not gone away.
 
Doing the water changes as i was told as well as fixing the ammonia and nitrite spike i had, the red gills have yet to go away.
 
So my question would be, what medicine(all natural if possible) could i use to try to combat this red gill disease(or parasite) as it looks like my danios have a silver bubble where their gills should be. Should i put them in a different tank and try to fix it there? or since my other fish may have it, but the other fish dont show the symptoms as of right now.
 
Water Parameters
20Gal tank
Ammonia 0.0
Nirtite 0.0
Nitrate 40 PPm( dont know if this is good as ive managed to keep it stable at 20 before this happened)
 
Ph 7.8
Gh 6
Kh N/a
 
Temperature 78* F 25*C
Also by the looks of it my Tank has alot of Magnesium(Mg) which i can assume would be a factor in this red-gill problem
 
 

 

[BaylorPerez]

UPDATE
 
Looking at some forums it looks like they suggest it could be gill Flukes?.
What are these gill Flukes(if thats what they are), and what can i do to fix this.
 
Also, they are not  scratching agaisnt my plant leaves or ornament so i dont know if thats what they are.
 
Will add photos to help try to solve this issue
Tried to add photos but the most i could get was some of their red tinted bodys

 

[SherLar]

   I've never had gill flukes, so I can't speak to that. But, when all other remedies and meds fail me (Pimafix for bacterial and Melafix for fungal usually work great for me), we usually use Maracyn, Maracyn-2, and in severe cases, FishPen.

 

[BaylorPerez]

are those parasite removers?