Dark Raised Patches On Senegal Bichir

[Deroplatys]

Hes had them since i got him, doesnt seem to affect him in anyway but i've finally got a picture that shows them and i want to find out what it is.

Any idea what it is?
They seem very slightly raised although im not too sure.

Forgot i posted this before, had a look at the old thread and no its not slime coat removal, hes always had them

 

[WILDER]

Can you describe in more detail what you see.

Has he lost weight?
Is the fish also acting listless and lethargic?

 

[Deroplatys]

I dont think hes lost wieght, havent noticed and he still has one hell of an epetite when it comes to worms. He's always swimming around and seems perfectly normal. My first and only bichir but he's had them since i got him.