White patches (not dots)

Hello guys! Yesterday I've been informed that my albino alfa male has died.
Today my brother told me that the fish from the same aquarium (albino bristlenoses plus 1xL144) have some whitish patches and they look a bit discolored.
I have no clue what is about because didn't had this problem before.
The main problem is that I'm working on a merchant vessel and will be home end of the month.
Can you please advice any medication or any suggestion will be appreciated.
Thank you!

how experienced is your brother with fish. sounds like ammonia burn to me

For sure ia not amonia! The paraneters are ok!
Not quite an aquarist let's say! I don't believe theyy had any problems the only thing which concerned me was the fact that the biggest male I had deied . They look to be ok now. Saw some pictures.
Thnks for the reply Doug! Always very kind to help!
Cheers!