Red Arowana with 2 scales that have black dots and is darker then the rest

[Reach]

Hello everyone, currently it has been 3 days now and on the first day that I have noticed, the 2 scales were almost completely dark but today it’s breaking down and going into like small dots on those 2 scales. What can I do to solve this and what’s the cause? Thank you guys in advance

 

[A201]

Looks like some type of tank debris has settled on the scales.
The Arowana' constant swimming is gradually breaking up the problem.

 

[Reach]

It’s definitely not debris.. it must be something else since the color doesn’t look like it’s debris, the entire scale is gray

Looks like some type of tank debris has settled on the scales.
The Arowana' constant swimming is gradually breaking up the problem.

 

[RealCrix220]

my first though was damage, it may have jumped or spun round into something in the tank.

Mine did this a few times and had marks on it but they did go with some good water changes and a touch of aquarium salt

 

[SilverArowBboy15]

btw is it an dirt or an scratch?