Recently added 6 silver Dollars

[MajorGFX]

I recently added 6 Silver Dollars to my newly cycled tank.

Amm 0
Nitri 0
Nitrates 40PPM (Bringing them down daily)
PH 8.0
Temp 26C

3 out of the 6 have developed behavior that may seem like swim bladder issues.

Basically they are swimming head down (to stop them floating to the top)

Originally it was just 1, now 3...

They were eating fine the day I got them, fed on flake.

any ideas why this has happened? Anything I can do to either help them or stop the rest from developing this?

 

[MajorGFX]

UPDATE:

2 of them are much better today. 1 of them seems to be swimming better, but is skimming the bottom of the substrate while swimming around rather than floating up.

Feeding well on Flake still. Tried some Peas but they were untouched.