Angel fish problem ?

[Taras1987]

Good morning
I am new to the page

I recently purchased 3 angel fish , the water was tested before hand by myself and the shop I purchased the fish from
The fish developed these black marks over the course of the afternoon
I thought initially there was an issue with the water but again I tested everything and it was fine
Any ideas what this could be
Many thanks
Tara.

 

[fishingBuds]

Its called pigmentation, i had 5 engel fosh at once and they change colors when they growing, since yours looks super ypung he will change a lot.
If you talking about something else, please take a closer picture to the isse, but as far as i can see, its just nature