Platy shedding scales??

[janice_016]

Looks like my platy is shedding scales, her one side is shiny and losing colour. Is this bacterial or fungas? I have medication for both not sure what one I should use. Please help? Thank you

 

[janice_016]

Tank is 36 gallons

Ph is 7.0

Ammonia is 0

Nitrites is 0

Nitrates is 20

Temp is 75



Have 4 platys

3 zebra danios

2 black skirts. ( yes I know they are schooling fish but every time I add more the two I have get aggressive, they are happy just the 2 of them and not aggressive)

1 sucker fish. Dont know what kind. Had him for 5 + yrs. he's about 4 inches max

10 guppies including a few fry

4 neon Tetra.

My tank is a bit over stocked for my liking. The guppies will be going to a friends soon.

Regular water changes, weekly about 25%.

 

[janice_016]

Here's a pic. Thanks!!

 

[Delapool]

Also pretty stuck on this. One thought, could it be the sucking catfish attacking and ripping off scales? My neighbor has complained of this and I've read but never had any trouble.