Angelfish cant close mouth, Cottonmouth??

[Coop23]

Hey everyone.
Just got this pair of angels given to me from someone that couldnt care for them anymore.
They have been in there tank for 3 days now and i have noticed something is wrong with the male...
He has his mouth open 24/7 and cant seem to close it. I didnt think much at it at the time but as i looked
further i noticed some white stuff around his mouth aswell. The 2 angels are in a 20 gallon breeding tank right now
and i am doing 50 percent every 3 days. On hand right now i have melafix, multi cure, ichonex by aquasonic, and salt of course.
What is the best way of treating this, thanks everyone!!

 

[DoubleDutch]

Could they have been fighting ?

 

[Coop23]

Could they have been fighting ?

They have been flashing there fins and stuff, that is normal breeding behaviour for pairs? But no fights, or aggressive behaviour, only breeding/spawning behaviour.