White slash on side of Betta fish

My Betta has a white mark on his side that has been there for over one month. His behavior and appetite are normal. I thought maybe he injured himself and it would heal with water changes but it's staying the same .

He is alone in a 15 gal planted, heated tank with no ammonia or nitrite. He was a rescue fish so I am not sure how old he is but I do know that he was neglected at the pet store so he may have some health problems.

Do anyone recognize what this white mark could be? It isn't getting bigger in size but it isn't going away either.

Thank you

I can't really say but, to me, it looks like an injury with a loss of scales.

jaylach said:

I can't really say but, to me, it looks like an injury with a loss of scales.

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thank you so much for the response.