Help !!!Tetra doing poorly

[Dubby]

My head & tail lights tetra is suffering. She has nearly lost her balance (swimming head higher than tail), has reddish patches at the joint of her pectoral fins and is not too keen on eating.

Her fins are fine otherwise, no damage or discoloration or spots.

Water params are fine.

What could it be?

 

[The-Wolf]

could be gill flukes
try this link

 

[corrosive]

could be gill flukes
try this link

link isnt working?

 

[Dubby]

Thanks. I have placed her in a salt bath for 2 days and red patches & swimming seem to be a little better. She has not started to eat in earnest so I am still worried.