Hexamita and Fish facing backwards

[batang_mcdo]

Have you tested your water?

Yes

If yes, what is your ammonia?

0

If yes, what is your nitrite?

0

If yes, what is your nitrate?

80

If I did not test my water...

...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

21-30%

How frequently do you change your water?

Every week

If I do not change my water...

...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

I noticed before with discus that has hexamita, one of the signs is they will be facing the back of the tank besides the whiting poop.
Anybody noticed this in other fish? I have a Stingray which i noticed is facing the back all the time, its not active, sunken back/skinny.
Thinking if this could be a case of hexamita. I have not seen any poop from here too.
this is my friend's Ray, i should not have added her into my ray tank my one male ray that is with her, his appetite has also decreased.
not sure if i should suspect hexamita . I have gone through 2 rounds of prazi already. now just doing daily 30% water change on my tank.

Tank's temperature is set to 28 Deg Celcius.
tank is 350 gallon tank with 180 gallon sump
current inhabitants are 2 13-14 inch rays, 8 pcs 6-8 inch clown loaches and a 7 inch NGT.

the new female ray has been with me for 10 days.